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Sample records for analysing tidally induced

  1. Simulations of the grand design galaxy M51: a case study for analysing tidally induced spiral structure

    Science.gov (United States)

    Dobbs, C. L.; Theis, C.; Pringle, J. E.; Bate, M. R.

    2010-04-01

    We present hydrodynamical models of the grand design spiral M51 (NGC 5194), and its interaction with its companion NGC 5195. Despite the simplicity of our models, our simulations capture the present-day spiral structure of M51 remarkably well, and even reproduce details such as a kink along one spiral arm, and spiral arm bifurcations. We investigate the offset between the stellar and gaseous spiral arms, and find at most times (including the present day) there is no offset between the stars and gas within our error bars. We also compare our simulations with recent observational analysis of M51. We compute the pattern speed versus radius, and similar to observations, find no single global pattern speed. We also show that the spiral arms cannot be fitted well by logarithmic spirals. We interpret these findings as evidence that M51 does not exhibit a quasi-steady density wave, as would be predicted by density wave theory. The internal structure of M51 derives from the complicated and dynamical interaction with its companion, resulting in spiral arms showing considerable structure in the form of short-lived kinks and bifurcations. Rather than trying to model such galaxies in terms of global spiral modes with fixed pattern speeds, it is more realistic to start from a picture in which the spiral arms, while not being simple material arms, are the result of tidally induced kinematic density `waves' or density patterns, which wind up slowly over time.

  2. Tidally Induced Bars of Galaxies in Clusters

    Science.gov (United States)

    Łokas, Ewa L.; Ebrová, Ivana; del Pino, Andrés; Sybilska, Agnieszka; Athanassoula, E.; Semczuk, Marcin; Gajda, Grzegorz; Fouquet, Sylvain

    2016-08-01

    Using N-body simulations, we study the formation and evolution of tidally induced bars in disky galaxies in clusters. Our progenitor is a massive, late-type galaxy similar to the Milky Way, composed of an exponential disk and a Navarro-Frenk-White dark matter halo. We place the galaxy on four different orbits in a Virgo-like cluster and evolve it for 10 Gyr. As a reference case, we also evolve the same model in isolation. Tidally induced bars form on all orbits soon after the first pericenter passage and survive until the end of the evolution. They appear earlier, are stronger and longer, and have lower pattern speeds for tighter orbits. Only for the tightest orbit are the properties of the bar controlled by the orientation of the tidal torque from the cluster at pericenter. The mechanism behind the formation of the bars is the angular momentum transfer from the galaxy stellar component to its halo. All of the bars undergo extended periods of buckling instability that occur earlier and lead to more pronounced boxy/peanut shapes when the tidal forces are stronger. Using all simulation outputs of galaxies at different evolutionary stages, we construct a toy model of the galaxy population in the cluster and measure the average bar strength and bar fraction as a function of clustercentric radius. Both are found to be mildly decreasing functions of radius. We conclude that tidal forces can trigger bar formation in cluster cores, but not in the outskirts, and thus can cause larger concentrations of barred galaxies toward the cluster center.

  3. Adventures of a tidally induced bar

    CERN Document Server

    Lokas, E L; Debattista, V P; Valluri, M; del Pino, A; Semczuk, M; Gajda, G; Kowalczyk, K

    2014-01-01

    Using N-body simulations, we study the properties of a bar induced in a dwarf galaxy as a result of tidal interaction with the Milky Way. The dwarf is initially composed of a disk embedded in a dark matter halo and we follow its evolution on a typical orbit for 10 Gyr. It undergoes an evolution typical of tidally stirred dwarf galaxies: it loses mass, the stellar component transforms from a disk to a spheroid and the rotation of the stars is partially replaced by random motions. A tidally induced bar forms at the first pericentre passage and survives until the end of the evolution. Fourier decomposition of the distribution of stars reveals that only even modes are significant and preserve a hierarchy so that the bar mode is always the strongest. They show a characteristic profile with a maximum, similar to simulated bars forming in isolated galaxies and observed bars in real galaxies. We adopt the maximum of the bar mode as a measure of the bar strength and we estimate the bar length by comparing the density ...

  4. Tidally induced lateral dispersion of the Storfjorden overflow plume

    Directory of Open Access Journals (Sweden)

    F. Wobus

    2013-10-01

    Full Text Available We investigate the flow of brine-enriched shelf water from Storfjorden (Svalbard into Fram Strait and onto the western Svalbard Shelf using a regional set-up of NEMO-SHELF, a 3-D numerical ocean circulation model. The model is set up with realistic bathymetry, atmospheric forcing, open boundary conditions and tides. The model has 3 km horizontal resolution and 50 vertical levels in the sh-coordinate system which is specially designed to resolve bottom boundary layer processes. In a series of modelling experiments we focus on the influence of tides on the propagation of the dense water plume by comparing results from tidal and non-tidal model runs. Comparisons of non-tidal to tidal simulations reveal a hotspot of tidally induced horizontal diffusion leading to the lateral dispersion of the plume at the southernmost headland of Spitsbergen which is in close proximity to the plume path. As a result the lighter fractions in the diluted upper layer of the plume are drawn into the shallow coastal current that carries Storfjorden water onto the western Svalbard Shelf, while the dense bottom layer continues to sink down the slope. This bifurcation of the plume into a diluted shelf branch and a dense downslope branch is enhanced by tidally induced shear dispersion at the headland. Tidal effects at the headland are shown to cause a net reduction in the downslope flux of Storfjorden water into the deep Fram Strait. This finding contrasts previous results from observations of a dense plume on a different shelf without abrupt topography.

  5. Preliminary assessment of landslide-induced wave hazards, Tidal Inlet, Glacier Bay National Park, Alaska

    Science.gov (United States)

    Wieczorek, Gerald F.; Jakob, Matthias; Motyka, Roman J.; Zirnheld, Sandra L.; Craw, Patricia

    2003-01-01

    A large potential rock avalanche above the northern shore of Tidal Inlet, Glacier Bay National Park, Alaska, was investigated to determine hazards and risks of landslide-induced waves to cruise ships and other park visitors. Field and photographic examination revealed that the 5 to 10 million cubic meter landslide moved between AD 1892 and 1919 after the retreat of Little Ice Age glaciers from Tidal Inlet by AD 1890. The timing of landslide movement and the glacial history suggest that glacial debuttressing caused weakening of the slope and that the landslide could have been triggered by large earthquakes of 1899-1900 in Yakutat Bay. Evidence of recent movement includes fresh scarps, back-rotated blocks, and smaller secondary landslide movements. However, until there is evidence of current movement, the mass is classified as a dormant rock slump. An earthquake on the nearby active Fairweather fault system could reactivate the landslide and trigger a massive rock slump and debris avalanche into Tidal Inlet. Preliminary analyses show that waves induced by such a landslide could travel at speeds of 45 to 50 m/s and reach heights up to 76 m with wave runups of 200 m on the opposite shore of Tidal Inlet. Such waves would not only threaten vessels in Tidal Inlet, but would also travel into the western arm of Glacier Bay endangering large cruise ships and their passengers.

  6. Tidal-induced lopsidedness in Magellanic-type galaxies

    CERN Document Server

    Yozin, Cameron

    2014-01-01

    We investigate the tidally-induced conversion of barred late-type spirals to Magellanic-type discs with numerical simulations, to establish how the lifetime of lopsidedness (asymmetry) varies with numerical parametrizations. Using a reference model based on observed properties of the Large Magellanic Cloud (LMC), we show that its off-centre bar, one-arm spiral and one-sided star formation can be induced by a brief tidal interaction. We thereafter perform a detailed parameter study, and find that at the dynamical mass of LMC-type discs ($\\sim$10$^{\\rm 10}$ \\md{}), stellar lopsidedness (as quantified by the m$=$1 Fourier mode) and bar off-centredness can vary widely in amplitude, but are generally short-lived ($\\sim$Gyr). Tidal interactions induce more persistent lopsidedness in lower mass galaxies (several Gyr), in particular those with large halo-to-disc mass ratios as implied by recent halo occupation models. We suggest that the tidal interactions play a larger role in the observed ubiquity of lopsidedness t...

  7. The orbital structure of a tidally induced bar

    CERN Document Server

    Gajda, Grzegorz; Athanassoula, E

    2016-01-01

    Orbits are the key building blocks of any density distribution and their study helps us understand the kinematical structure and the evolution of galaxies. Here we investigate orbits in a tidally induced bar of a dwarf galaxy, using an $N$-body simulation of an initially disky dwarf galaxy orbiting a Milky Way-like host. After the first pericenter passage, a tidally induced bar forms in the stellar component of the dwarf. The bar evolution is different than in isolated galaxies and our analysis focuses on the period before it buckles. We study the orbits in terms of their fundamental frequencies, which we calculate in a Cartesian coordinate frame rotating with the bar. Apart from the well-known x$_1$ orbits we find many other types, mostly with boxy shapes of various degree of elongation. Some of them are also near-periodic, admitting frequency ratios of 4/3, 3/2 and 5/3. The box orbits have various degrees of vertical thickness but only a relatively small fraction of those have banana (i.e. smile/frown) or i...

  8. The Orbital Structure of a Tidally Induced Bar

    Science.gov (United States)

    Gajda, Grzegorz; Łokas, Ewa L.; Athanassoula, E.

    2016-10-01

    Orbits are the key building blocks of any density distribution, and their study helps us understand the kinematical structure and the evolution of galaxies. Here, we investigate orbits in a tidally induced bar of a dwarf galaxy, using an N-body simulation of an initially disky dwarf galaxy orbiting a Milky Way-like host. After the first pericenter passage, a tidally induced bar forms in the stellar component of the dwarf. The bar evolution is different than in isolated galaxies and our analysis focuses on the period before it buckles. We study the orbits in terms of their dominant frequencies, which we calculate in a Cartesian coordinate frame rotating with the bar. Apart from the well-known x1 orbits, we find many other types, mostly with boxy shapes of various degree of elongation. Some of them are also near-periodic, admitting frequency ratios of 4/3, 3/2, and 5/3. The box orbits have various degrees of vertical thickness but only a relatively small fraction of those have banana (i.e., smile/frown) or infinity-symbol shapes in the edge-on view. In the very center we also find orbits known from the potential of triaxial ellipsoids. The elongation of the orbits grows with distance from the center of the bar in agreement with the variation of the shape of the density distribution. Our classification of orbits leads to the conclusion that more than 80% of them have boxy shapes, while only 8% have shapes of classical x1 orbits.

  9. Tidal motions and tidally induced fluxes through La Línea submarine canyon, western Alboran Sea

    Science.gov (United States)

    Lafuente, Jesús GarcíA.; Sarhan, Tarek; Vargas, Manuel; Vargas, Juan M.; Plaza, Francisco

    1999-02-01

    Detailed observations from two mooring lines deployed in La Línea submarine canyon, western Alboran Sea, are presented. This is a narrow canyon in the sense that its width is always less than the internal radius of deformation. Tidal currents within the canyon are polarized in the along-canyon direction according to its narrow nature. They have considerable amplitude (values of around 0.5 m/s are often observed) and are forced by the internal pressure gradients associated with the baroclinic tide that is generated in the surroundings. Subsequent amplification of onshore baroclinic currents within the canyon accounts for the large amplitude observed. Cross-shelf exchange through the canyon due to tidal motions is different from zero despite the close to zero mean of tidal currents. The explanation is based on the asymmetry of water properties flowing up-canyon and down-canyon (some sort of tidal rectification). Regarding the energy flux, the canyon seems to be an adequate conduit to carry energy to the shore. Estimations made from our observations indicate that energy input onto the shelf per unit length parallel to the shore at the canyon head is enough to maintain mixing on the shelf at intermediate depths.

  10. Tidally Induced Elongation and Alignments of Galaxy Clusters

    CERN Document Server

    Salvador-Solé, E; Salvador-Sole, Eduard; Solanes, Jose M.

    1993-01-01

    We show that tidal interaction among galaxy clusters can account for their observed alignments and very marked elongation and, consequently, that these characteristics of clusters are actually consistent with them being formed in hierarchical clustering. The well-established distribution of projected axial ratios of clusters with richness class $R\\ge 0$ is recovered very satisfactorily by means of a simple model with no free parameters. The main perturbers are relatively rich ($R\\ge 1$) single clusters and/or groups of clusters (superclusters) of a wider richness class ($R\\ge 0$) located within a distance of about 65 $h^{-1}$ Mpc from the perturbed cluster. This makes the proposed scheme be also consistent with all reported alignment effects involving clusters. We find that this tidal interaction is typically in the saturate regime (\\ie the maximum elongation allowed for systems in equilibrium is reached), which explains the very similar intrinsic axial ratio shown by all clusters. Tides would therefore play ...

  11. Tidally Induced Pulsations in Kepler Eclipsing Binary KIC 3230227

    CERN Document Server

    Guo, Zhao; Fuller, Jim

    2016-01-01

    KIC 3230227 is a short period ($P\\approx 7.0$ days) eclipsing binary with a very eccentric orbit ($e=0.6$). From combined analysis of radial velocities and {\\it Kepler} light curves, this system is found to be composed of two A-type stars, with masses of $M_1=1.84\\pm 0.18M_{\\odot}$, $M_2=1.73\\pm 0.17M_{\\odot}$ and radii of $R_1=2.01\\pm 0.09R_{\\odot}$, $R_2=1.68\\pm 0.08 R_{\\odot}$ for the primary and secondary, respectively. In addition to an eclipse, the binary light curve shows a brightening and dimming near periastron, making this a somewhat rare eclipsing heartbeat star system. After removing the binary light curve model, more than ten pulsational frequencies are present in the Fourier spectrum of the residuals, and most of them are integer multiples of the orbital frequency. These pulsations are tidally driven, and both the amplitudes and phases are in agreement with predictions from linear tidal theory for $l=2, m=-2$ prograde modes.

  12. Tidal current-induced formation——storm-induced change——tidal current-induced recovery——Interpretation of depositional dynamics of formation and evolution of radial sand ridges on the Yellow Sea seafloor

    Institute of Scientific and Technical Information of China (English)

    张长宽; 张东生; 张君伦; 王震

    1999-01-01

    The results of simulated tidal current field, wave field and storm-induced current field are employed to interpret the depositional dynamic mechanism of formation and evolution of the radial sand ridges on the Yellow Sea seafloor. The anticlockwise rotary tidal wave to the south of Shandong Peninsula meets the following progressive tidal wave from the South Yellow Sea, forming a radial current field outside Jianggang. This current field provides a necessary dynamic condition for the formation and existence of the radial sand ridges on the Yellow Sea seafloor. The results of simulated "old current field (holocene)" show that there existed a convergent-divergent tidal zone just outside the palaeo-Yangtze River estuary where a palaeo-underwater accumulation was developed. The calculated results from wave models indicate that the wave impact on the topography, under the condition of high water level and strong winds, is significant. The storm current induced by typhoons landing in the Yangtze River estuary

  13. Experimental study of acute lung injury induced by different tidal volume ventilation in rats

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-ri; DU Yong-cheng; JIANG Hong-ying; XU Jian-ying; XU Yong-jian

    2005-01-01

    @@ Mechanical ventilation (MV) is a dual blade sward which if misused could lead to lung injury, called ventilator induced lung injury (VILI). Pathogenesis of VILI is very complex with various manifestations, which is the focus in MV field in recent years.1 In our research, the rats were ventilated with different tidal volume, then the pathological changes of the lungs were observed under macroscopy, light and electronic microscope, and various laboratory tests in blood and bronchoalveolar lavage fluid (BALF) were also carried out in order to probe further the pathologic characteristics and the pathogenesis of VILI.

  14. Direct estimation of tidally induced Earth rotation variations observed by VLBI

    Science.gov (United States)

    Englich, S.; Heinkelmann, R.; BOHM, J.; Schuh, H.

    2009-09-01

    The subject of our study is the investigation of periodical variations induced by solid Earth tides and ocean tides in Earth rotation parameters (ERP: polar motion, UT1)observed by VLBI. There are two strategies to determine the amplitudes and phases of Earth rotation variations from observations of space geodetic techniques. The common way is to derive time series of Earth rotation parameters first and to estimate amplitudes and phases in a second step. Results obtained by this means were shown in previous studies for zonal tidal variations (Englich et al.; 2008a) and variations caused by ocean tides (Englich et al.; 2008b). The alternative method is to estimate the tidal parameters directly within the VLBI data analysis procedure together with other parameters such as station coordinates, tropospheric delays, clocks etc. The purpose of this work was the application of this direct method to a combined VLBI data analysis using the software packages OCCAM (Version 6.1, Gauss-Markov-Model) and DOGSCS (Gerstl et al.; 2001). The theoretical basis and the preparatory steps for the implementation of this approach are presented here.

  15. Tidally induced variations in vertical and horizontal motion on Rutford Ice Stream, West Antarctica, inferred from remotely sensed observations

    Science.gov (United States)

    Minchew, B. M.; Simons, M.; Riel, B.; Milillo, P.

    2017-01-01

    To better understand the influence of stress changes over floating ice shelves on grounded ice streams, we develop a Bayesian method for inferring time-dependent 3-D surface velocity fields from synthetic aperture radar (SAR) and optical remote sensing data. Our specific goal is to observe ocean tide-induced variability in vertical ice shelf position and horizontal ice stream flow. Thus, we consider the special case where observed surface displacement at a given location can be defined by a 3-D secular velocity vector, a family of 3-D sinusoidal functions, and a correction to the digital elevation model used to process the SAR data. Using nearly 9 months of SAR data collected from multiple satellite viewing geometries with the COSMO-SkyMed 4-satellite constellation, we infer the spatiotemporal response of Rutford Ice Stream, West Antarctica, to ocean tidal forcing. Consistent with expected tidal uplift, inferred vertical motion over the ice shelf is dominated by semidiurnal and diurnal tidal constituents. Horizontal ice flow variability, on the other hand, occurs primarily at the fortnightly spring-neap tidal period (Msf). We propose that periodic grounding of the ice shelf is the primary mechanism for translating vertical tidal motion into horizontal flow variability, causing ice flow to accelerate first and most strongly over the ice shelf. Flow variations then propagate through the grounded ice stream at a mean rate of ˜29 km/d and decay quasi-linearly with distance over ˜85 km upstream of the grounding zone.

  16. Natural and human-induced driving factors in the evolution of tidal channels: case studies in the Venice Lagoon (Italy).

    Science.gov (United States)

    Rizzetto, Federica

    2013-04-01

    Coastal wetlands are largely affected by a complex variety of both natural and anthropogenic factors, which induce evident, often irreversible, geomorphological transformations. In particular, this research focuses on the main processes that influence the evolution of tidal channels in salt marshes and shows the results derived from the analysis of some case studies in the Venice Lagoon (northwestern Adriatic Sea, Italy). Here tidal network has been recognized as significantly sensitive to sea-level rise and tide oscillations (Rizzetto and Tosi, 2011; Rizzetto and Tosi, 2012), but it is also vulnerable to human impact. The sites were selected in areas characterized by low anthropogenic pressure to prevent strong human interferences from completely masking the effects of natural forces. The interpretation of a large number of high-resolution aerial photographs, taken since the mid 1930s, allowed identifying in detail tidal channel evolution, both in the long- and in the short-term. The observation of historical and recent topographic maps completed the study and provided other important data to define the modifications occurred in the past two centuries. The channel planform changes were determined through the morphometric analysis of the tidal network, carried out using a Geographic Information System software. These modifications were interpreted in the light of sea-level oscillations (i.e. relative sea-level rise and strength/frequency of high tides, which are increasing owing to climate changes), variations of sediment supply, and human activities occurred in the past century. The joint analysis of all the data allowed distinguishing the changes induced by both relative sea-level rise and high tides on planform pattern and evolution of tidal channels, and identifying the effects of human interferences, which magnified the impact of natural factors (e.g. groundwater exploitation responsible for high subsidence rates between 1950 and 1970 and, consequently, for an

  17. Sand-Mud Sediment Transport induced by tidal currents and wind waves in shallow microtidal basins

    Science.gov (United States)

    Carniello, L.; Defina, A.; D'Alpaos, L.

    2011-12-01

    Field data and mathematical modeling have demonstrated that the morphological evolution of shallow tidal basins is the result of the combined effect of tidal currents and wind waves. Tidal currents, in particular, drive the morphological evolution of shallow tidal systems in proximity of the inlets and within the channel network, whereas in shallow areas tidal current mainly acts enhancing the bottom shear stress due to wind waves and redistributing sediments within the basin. In this study we present a mathematical model for sediment entrainment, transport and deposition due to the combined effect of tidal currents and wind waves. The model is coupled with a hydrodynamic module based on the shallow water equations and with a module for the generation and propagation of wind waves. The sediment transport model describes the sediments by the way of a bi-granular mixtures composed by both cohesive and non-cohesive sediments thus considering the contemporary presence of clay, silt and sand which usually characterizes estuaries and tidal basins. Moreover, the model describes the bed evolution and evaluates the variation of bed sediment composition considering also the transition between cohesive and non-cohesive behavior. Attention is focused on some issues concerning the definition of a reliable initial bed composition and the incipient sediment motion which is treated following a stochastic approach for the bottom shear stress and for the critical shear stress distribution. The model is applied to the Lagoon of Venice (Italy) and the results of different simulations are compared, with good agreement, to a series of turbidity measurements collected inside the lagoon. The application of the model to the present bathymetry of the Venice lagoon allows for a first estimation of the actual net amount of sand and mud flowing through the three inlets and also gives some information on bottom evolution in terms of elevation and composition.

  18. Environmental change on tidal flat induced by anthropogenic effect around west coast of Korean Peninsula

    Science.gov (United States)

    Lee, Yoon-Kyung; Choi, Jong-Kuk; Ryu, Joo-Hyung; Eom, Jinah

    2014-05-01

    Tidal flats are valuable ecosystem by a productive flora and fauna which support large populations of birds, form nursery and feeding areas for coastal fisheries, provide intrinsic values such as aesthetics and education (Costanza et al., 1997; Goodwin et al., 2001). The half of the world's coastal wetlands will submerge during this century in response to sea level rise although salt marsh has a capacity to adjust to sea level rise change. However, tidal flats have been changed because of several coastal construction projects that had not been considered sustainable over the last 30 years in Korean Peninsula. The total area of tidal flats decreased from approximately 2,800 km2 in 1990 to 2,393 km2 in 2005 due to the land reclamations and dredging in South Korea. Many researchers investigated topography, sedimentation changes and local hydrodynamics for this area in the early 1990s. However, they are limited to the temporal and spatial scale because field surveys in the tidal flats are restricted due to the difficulties in accessing. The aim of this study was to examine environmental change in tidal flat in a large scale for long-term based on the remotely sensed data as well as in situ measurements. This study focused on the tidal flat that not only had been affected by reclamations on a large scale such as Ganghwa and Saemangeum but also had been indirectly affected by reclamations such as Hwang-do and Gomso-bay. In this study, changes in morphology and sedimentary facies in tidal flats were estimated. Digital elevation models (DEMs) in early 2000 and 2010 were generated based on the Landsat TM/ETM+ images using a waterline method. Morphological change was estimated based on the differences of DEMs and sedimentary facies was investigated based on the calculation of image-derived PCA coefficient. Results of the morphological change in tidal flats interestingly showed that large amount of areas had been deposited whereas the other areas were eroded. Area with

  19. Feedback between tidal hydrodynamics and morphological changes induced by natural process and human interventions in a wave-dominated tidal inlet: Xiaohai, Hainan, China

    Institute of Scientific and Technical Information of China (English)

    GONG Wenping; SHEN Jian; JIA Jianjun

    2009-01-01

    The feedback between morphological evolution and tidal hydrodynamics in a wave-dominated tidal inlet, Xiaohai, China is investigated through data analysis and numerical model experiments. His-torically, Xiaohai Inlet had two openings, located at the north and south of Neizhi Island (a rocky outcrop), respectively. The evolution of Xiaohai Inlet was dominated by the natural process be-fore 1972. In addition to the natural process, human interventions, including the closure of the north opening, 50% of freshwater reduction, and increase of land reclamation, have altered tidal hydrodynamics and morphological evolution since 1972. A series of numerical model simulations were conducted to investigate the influence of morphological changes on the hydrodynamics and the influence of human activities on the inlet evolution. The natural process has caused narrowing and shoaling of the inlet throat, development of the flood-tidal delta, and shoaling of the tidal channel inside the lagoon. Human interventions have accelerated these changes. Consequently, the tidal propagation from the offshore into the lagoon has been impeded and the tidal energy has been dissipated substantially. Tidal current has changed from ebb-dominant to flood-dominant in most parts of the inlet system whereas the inlet throat has remained as ebb-dominant, the tidal prism has decreased consistently, and sediment has continued to deposit inside the inlet. As a result, the changes of morphology, hydrodynamics, and sediment transport show a positive feedback. The human interventions have had both advantageous and adverse influences on the stability of the inlet. The closure of the North Opening has decreased the longshore sediment input to the inlet, and increased the tidal prism, ebb velocity, and sediment transport in the south opening, thus enhancing the inlet's stability. However, reducing the river discharge and landfill of the tidal flats has resulted in a decrease of the tidal prism, the ebb velocity

  20. Thermohaline circulation below the Ross Ice Shelf - A consequence of tidally induced vertical mixing and basal melting

    Science.gov (United States)

    Macayeal, D. R.

    1984-01-01

    The warmest water below parts of the Ross Ice Shelf resides in the lowest portion of the water column because of its high salinity. Vertical mixing caused by tidal stirring can thus induce ablation by lifting the warm but dense water into contact with the ice shelf. A numerical tidal simulation indicates that vertically well-mixed conditions predominate in the southeastern part of the sub-ice shelf cavity, where the water column thickness is small. Basal melting in this region is expected to be between 0.05 and 0.5 m/yr and will drive a thermohaline circulation having the following characteristics: high salinity shelf water (at - 1.8 C), formed by winter sea ice production in the open Ross Sea, flows along the seabed toward the tidal mixing fronts below the ice shelf; and meltwater (at -2.2 C), produced in the well-mixed region, flows out of the sub-ice shelf cavity along the ice shelf bottom. Sensitivity of this ablation process to climatic change is expected to be small because high salinity shelf water is constrained to have the sea surface freezing temperature.

  1. Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating

    CERN Document Server

    Barnes, Rory; Goldblatt, Colin; Meadows, Victoria S; Kasting, James F; Heller, Rene

    2012-01-01

    Traditionally stellar radiation has been the only heat source considered capable of determining global climate on long timescales. Here we show that terrestrial exoplanets orbiting low-mass stars may be tidally heated at high enough levels to induce a runaway greenhouse for a long enough duration for all the hydrogen to escape. Without hydrogen, the planet no longer has water and cannot support life. We call these planets "Tidal Venuses," and the phenomenon a "tidal greenhouse." Tidal effects also circularize the orbit, which decreases tidal heating. Hence, some planets may form with large eccentricity, with its accompanying large tidal heating, and lose their water, but eventually settle into nearly circular orbits in the habitable zone (HZ). However, these planets are not habitable as past tidal heating desiccated them, and hence should not be ranked highly for detailed follow-up observations aimed at detecting biosignatures. We simulate the evolution of hypothetical planetary systems in a quasi-continuous ...

  2. The tidally induced warping, precession and truncation of accretion discs in binary systems three dimensional simulations

    CERN Document Server

    Larwood, J D; Papaloizou, J C B; Terquem, C

    1996-01-01

    We present the results of non linear, hydrodynamic simulations, in three dimensions, of the tidal perturbation of accretion discs in binary systems where the orbit is circular and not necessarily coplanar with the disc mid-plane. The accretion discs are assumed to be geometrically thin, and of low mass relative to the stellar mass so that they are governed by thermal pressure and viscosity, but not self-gravity. The parameters that we consider in our models are the ratio of the orbital distance to the disc radius, D/R, the binary mass ratio, the initial inclination angle between the orbit and disc planes and the Mach number in the outer parts of the unperturbed disc. For binary mass ratios of around unity and D/R in the range 3 to 4, we find that the global evolution of the discs is governed primarily by the value of the Mach number. For relatively low Mach numbers (i.e. 10 to 20) we find that the discs develop a mildly warped structure, are tidally truncated, and undergo a near rigid body precession at a rat...

  3. TIDALLY INDUCED APSIDAL PRECESSION IN DOUBLE WHITE DWARFS: A NEW MASS MEASUREMENT TOOL WITH LISA

    Energy Technology Data Exchange (ETDEWEB)

    Valsecchi, F.; Farr, W. M.; Willems, B.; Deloye, C. J.; Kalogera, V. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

    2012-02-01

    Galactic interacting double white dwarfs (DWDs) are guaranteed gravitational wave (GW) sources for the Laser Interferometer Space Antenna GW detector, with more than 10{sup 4} binaries expected to be detected over the mission's lifetime. Part of this population is expected to be eccentric, and here we investigate the potential for constraining the white dwarf (WD) properties through apsidal precession in these binaries. We analyze the tidal, rotational, and general relativistic contributions to apsidal precession by using detailed He WD models, where the evolution of the star's interior is followed throughout the cooling phase. In agreement with previous studies of zero-temperature WDs, we find that apsidal precession in eccentric DWDs can lead to a detectable shift in the emitted GW signal when binaries with cool (old) components are considered. This shift increases significantly for hot (young) WDs. We find that apsidal motion in hot (cool) DWDs is dominated by tides at orbital frequencies above {approx}> 10{sup -4} Hz (10{sup -3} Hz). The analysis of apsidal precession in these sources while ignoring the tidal component would lead to an extreme bias in the mass determination, and could lead us to misidentify WDs as neutron stars or black holes. We use the detailed WD models to show that for older, cold WDs, there is a unique relationship that ties the radius and apsidal precession constant to the WD masses, therefore allowing tides to be used as a tool to constrain the source masses.

  4. Earth Inner Core Periodic Motion due to Pressure Difference Induced by Tidal Acceleration

    CERN Document Server

    Wolf, M

    2013-01-01

    The inner structure of the earth is still a topic of discussion. Seismic measurements showed a structure of solid, liquid, solid which describes the mantle, outer core and inner core with the inner core in the center. The analysis of waveform doublets suggests now that the inner core is out of center and even of faster rotation than the mantel and crust. From the sum of Buoyancy and Gravity on the earth inner core, the position energy is plotted and together with the tangential tidal acceleration, it is derived that Earth Inner Core cannot be in a center position without additional force. The Earth Core System is explained as Hydrodynamic Bearing. The Eccentricities out of nutation due to the effects from the sun and moon are calculated as an approximation.

  5. Tidally-Induced Apsidal Precession in Double White Dwarfs: a new mass measurement tool with LISA

    CERN Document Server

    Valsecchi, Francesca; Willems, Bart; Deloye, Christopher J; Kalogera, Vassiliki

    2011-01-01

    Galactic interacting double white dwarfs (DWD) are guaranteed gravitational wave (GW) sources for the GW detector LISA, with more than 10^4 binaries expected to be detected over the mission's lifetime. While the majority of DWDs are expected to be circular, dynamical interactions in globular clusters can lead to a sub-population of eccentric DWDs detectable by LISA. Here we investigate the potential for constraining the white dwarf (WD) properties through apsidal precession in these binaries. We analyze the tidal, rotational, and general relativistic contributions to apsidal precession by using detailed He WD models, where the evolution of the star's interior is followed throughout the cooling phase. In agreement with previous studies of zero-temperature WDs, we find that apsidal precession in eccentric DWDs can lead to a detectable shift in the emitted GW signal when binaries with cool (old) components are considered. This shift increases significantly for hot (young) WDs. We find that apsidal motion in hot ...

  6. Temporal variations in the flow of a large Antarctic ice-stream controlled by tidally induced changes in the subglacial water system

    Directory of Open Access Journals (Sweden)

    S. H. R. Rosier

    2015-04-01

    7 × 109 m2d-1, with sliding law exponents m = 3 and q =10. Coupled model results show the presence of tides result in a ~ 12% increase in mean surface velocity. Observations of tidally-induced variations in flow of ice-streams provide stronger constraints on basal sliding processes than provided by any other set of measurements.

  7. Transcutaneous vagus nerve stimulation induces tidal melatonin secretion and has an antidiabetic effect in Zucker fatty rats.

    Directory of Open Access Journals (Sweden)

    Shuxing Wang

    Full Text Available Melatonin plays a protective role in type 2 diabetes (T2D through regulation of glucose metabolism. Whether transcutaneous vagus nerve stimulation (taVNS is antidiabetic and whether a modulated melatonin production is involved in the antidiabetic mechanism of taVNS is unknown. In this study, once daily 30 min noninvasive taVNS was administered in Zucker diabetic fatty (ZDF, fa/fa and Zucker lean (ZL, +/fa littermates under anesthesia for 5 consecutive weeks. The acute and chronic influences of taVNS on the secretion of melatonin were studied as well as the effects of taVNS on blood glucose metabolism. We found that naïve ZDF rats develop hyperglycemia naturally with age. Each taVNS session would trigger a tidal secretion of melatonin both during and after the taVNS procedure and induce an acute two-phase glycemic change, a steep increase followed by a gradual decrease. Once daily taVNS sessions eventually reduced the glucose concentration to a normal level in seven days and effectively maintained the normal glycemic and plasma glycosylated hemoglobin (HbAlc levels when applied for five consecutive weeks. These beneficial effects of taVNS also exist in pinealectomized rats, which otherwise would show overt and continuous hyperglycemia, hyperinsulinemia, and high HbAlc levels. We concluded that multiple taVNS sessions are antidiabetic in T2D through triggering of tidal secretion of melatonin. This finding may have potential importance in developing new approaches to the treatment of T2D, which is highly prevalent, incurable with any current approaches, and very costly to the world.

  8. Transcutaneous vagus nerve stimulation induces tidal melatonin secretion and has an antidiabetic effect in Zucker fatty rats.

    Science.gov (United States)

    Wang, Shuxing; Zhai, Xu; Li, Shaoyuan; McCabe, Michael F; Wang, Xing; Rong, Peijing

    2015-01-01

    Melatonin plays a protective role in type 2 diabetes (T2D) through regulation of glucose metabolism. Whether transcutaneous vagus nerve stimulation (taVNS) is antidiabetic and whether a modulated melatonin production is involved in the antidiabetic mechanism of taVNS is unknown. In this study, once daily 30 min noninvasive taVNS was administered in Zucker diabetic fatty (ZDF, fa/fa) and Zucker lean (ZL, +/fa) littermates under anesthesia for 5 consecutive weeks. The acute and chronic influences of taVNS on the secretion of melatonin were studied as well as the effects of taVNS on blood glucose metabolism. We found that naïve ZDF rats develop hyperglycemia naturally with age. Each taVNS session would trigger a tidal secretion of melatonin both during and after the taVNS procedure and induce an acute two-phase glycemic change, a steep increase followed by a gradual decrease. Once daily taVNS sessions eventually reduced the glucose concentration to a normal level in seven days and effectively maintained the normal glycemic and plasma glycosylated hemoglobin (HbAlc) levels when applied for five consecutive weeks. These beneficial effects of taVNS also exist in pinealectomized rats, which otherwise would show overt and continuous hyperglycemia, hyperinsulinemia, and high HbAlc levels. We concluded that multiple taVNS sessions are antidiabetic in T2D through triggering of tidal secretion of melatonin. This finding may have potential importance in developing new approaches to the treatment of T2D, which is highly prevalent, incurable with any current approaches, and very costly to the world.

  9. Effects of Sediment-induced Stratification on Floc Breakup in an Idealized Tidal Estuary:A Numerical Modelling Study

    Institute of Scientific and Technical Information of China (English)

    X.H.Wang

    2004-01-01

    Floc breakup dynamics are studied by a sediment transport numerical model in an idealized tidal estuary that has a constant water depth and rapid flocculation of cohesive sediments. The focus is placed on the effects of boundary layer stratification induced by a bottom nepheloid layer on floc breakup and size distribution in the water column. In a neutrally stratified estuary, the floc size distribution follows a parabolic function with maximum values at the surface and bottom. The sediment-induced stratification in the bottom boundary layer increases the median floc sizes. Furthermore, sediment-voided convection caused by the settling lutocline generates significant turbulent kinetic energy dissipation and reduces floc size at the depth where the convective mixing happens. Below that depth, a weak local maxima in the floc size is predicted due to presence of the lutocline. The effect of sediment-stratified bottom boundary layer on the floc breakup can be consistently approximated by a linear regression between the maximal floc size and flux Richardson number.

  10. The mass of the neutron star in Vela X-1 and tidally induced non-radial oscillations in GP Vel

    CERN Document Server

    Quaintrell, H; Ash, T D C; Roche, P; Willems, B; Bedding, T R; Baldry, I K; Fender, R P

    2003-01-01

    We report new radial velocity observations of GP Vel/HD77581, the optical companion to the eclipsing X-ray pulsar Vela X-1. Using data spanning more than two complete orbits of the system, we detect evidence for tidally induced non-radial oscillations on the surface of GP Vel, apparent as peaks in the power spectrum of the residuals to the radial velocity curve fit. By removing the effect of these oscillations (to first order) and binning the radial velocities, we have determined the semi-amplitude of the radial velocity curve of GP Vel to be K_o=22.6+/-1.5 km/s. Given the accurately measured semi-amplitude of the pulsar's orbit, the mass ratio of the system is 0.081+/-0.005. We are able to set upper and lower limits on the masses of the component stars as follows. Assuming GP Vel fills its Roche lobe then the inclination angle of the system, i=70.1+/-2.6 deg. In this case we obtain the masses of the two stars as M_x=2.27 +/-0.17 M_sun for the neutron star and M_o=27.9+/-1.3 M_sun for GP Vel. Conversely, assu...

  11. The origin of type I profiles in cluster lenticulars: an interplay between ram pressure stripping and tidally induced spiral migration

    Science.gov (United States)

    Clarke, Adam J.; Debattista, Victor P.; Roškar, Rok; Quinn, Tom

    2017-02-01

    Using N-body + smooth particle hydrodynamics simulations of galaxies falling into a cluster, we study the evolution of their radial density profiles. When evolved in isolation, galaxies develop a type II (down-bending) profile. In the cluster, the evolution of the profile depends on the minimum cluster-centric radius the galaxy reaches, which controls the degree of ram pressure stripping. If the galaxy falls to ˜50 per cent of the virial radius, then the profile remains type II, but if the galaxy reaches down to ˜20 per cent of the virial radius, the break weakens and the profile becomes more type I like. The velocity dispersions are only slightly increased in the cluster simulations compared with the isolated galaxy; random motion therefore cannot be responsible for redistributing material sufficiently to cause the change in the profile type. Instead, we find that the joint action of radial migration driven by tidally induced spirals and the outside-in quenching of star formation due to ram pressure stripping alters the density profile. As a result, this model predicts a flattening of the age profiles amongst cluster lenticulars with type I profiles, which can be observationally tested.

  12. Tidal switch on metabolic activity: Salinity induced responses on bacterioplankton metabolic capabilities in a tropical estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Thottathil, S.D.; Balachandran, K.K.; Jayalakshmy, K.V.; Gupta, G.V.M.; Nair, S.

    for the present study, as it receives 35% of the total freshwater discharge through the River Periyar (Srinivas et al., 2003). Moreover, a fertilizer factory situated in the upstream north forms a major source of ammonia in the study region (Joy et al., 1990... mouth of the estuary. On the other hand, PCA indicates that amino/carboxylic acids are support- ing community metabolism at high salinity (Table 2). This shift can be due to the availability of substrates which induce bacterial cells to synthesize ecto...

  13. Simulations of the grand design galaxy M51: a case study for analysing tidally induced spiral structure

    CERN Document Server

    Dobbs, C L; Pringle, J E; Bate, M R

    2009-01-01

    We present hydrodynamical models of the grand design spiral M51 (NGC 5194), and its interaction with its companion NGC 5195. Despite the simplicity of our models, our simulations capture the present day spiral structure of M51 remarkably well, and even reproduce details such as a kink along one spiral arm, and spiral arm bifurcations. We investigate the offset between the stellar and gaseous spiral arms, and find at most times (including the present day) there is no offset between the stars and gas to within our error bars. We also compare our simulations with recent observational analysis of M51. We compute the pattern speed versus radius, and like the observations, find no single global pattern speed. We also show that the spiral arms cannot be fitted well by logarithmic spirals. We interpret these findings as evidence that M51 does not exhibit a quasi-steady density wave, as would be predicted by density wave theory. The internal structure of M51 derives from the complicated and dynamical interaction with ...

  14. Tidal deformations of a spinning compact object

    CERN Document Server

    Pani, Paolo; Maselli, Andrea; Ferrari, Valeria

    2015-01-01

    The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the multipole mom...

  15. Calculating lunar retreat rates using tidal rhythmites

    Science.gov (United States)

    Kvale, E.P.; Johnson, H.W.; Sonett, C.P.; Archer, A.W.; Zawistoski, A.N.N.

    1999-01-01

    Tidal rhythmites are small-scale sedimenta??r}- structures that can preserve a hierarchy of astronomically induced tidal periods. They can also preserve a record of periodic nontidal sedimentation. If properly interpreted and understood, tidal rhjthmites can be an important component of paleoastronomy and can be used to extract information on ancient lunar orbital dynamics including changes in Earth-Moon distance through geologic time. Herein we present techniques that can be used to calculate ancient Earth-Moon distances. Each of these techniques, when used on a modern high-tide data set, results in calculated estimates of lunar orbital periods and an EarthMoon distance that fall well within 1 percent of the actual values. Comparisons to results from modern tidal data indicate that ancient tidal rhythmite data as short as 4 months can provide suitable estimates of lunar orbital periods if these tidal records are complete. An understanding of basic tidal theory allows for the evaluation of completeness of the ancient tidal record as derived from an analysis of tidal rhythmites. Utilizing the techniques presented herein, it appears from the rock record that lunar orbital retreat slowed sometime during the midPaleozoic. Copyright ??1999, SEPM (Society for Sedimentary Geology).

  16. Seasonal variability of tidal and non-tidal currents off Beypore, SW coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    DineshKumar, P.K.; Srinivas, K.; AnilKumar, N.

    Analyses of current meter records generated in the coastal waters off Beypore (11 degrees 10 minutes S; 75 degrees 48 minutes E) on the southwest coast of India have been made to understand the tidal and non-tidal variability during premonsoon...

  17. Mechanical ventilation with high tidal volumes attenuates myocardial dysfunction by decreasing cardiac edema in a rat model of LPS-induced peritonitis

    Directory of Open Access Journals (Sweden)

    Smeding Lonneke

    2012-03-01

    Full Text Available Abstract Background Injurious mechanical ventilation (MV may augment organ injury remote from the lungs. During sepsis, myocardial dysfunction is common and increased endothelial activation and permeability can cause myocardial edema, which may, among other factors, hamper myocardial function. We investigated the effects of MV with injuriously high tidal volumes on the myocardium in an animal model of sepsis. Methods Normal rats and intraperitoneal (i.p. lipopolysaccharide (LPS-treated rats were ventilated with low (6 ml/kg and high (19 ml/kg tidal volumes (Vt under general anesthesia. Non-ventilated animals served as controls. Mean arterial pressure (MAP, central venous pressure (CVP, cardiac output (CO and pulmonary plateau pressure (Pplat were measured. Ex vivo myocardial function was measured in isolated Langendorff-perfused hearts. Cardiac expression of endothelial vascular cell adhesion molecule (VCAM-1 and edema were measured to evaluate endothelial inflammation and leakage. Results MAP decreased after LPS-treatment and Vt-dependently, both independent of each other and with interaction. MV Vt-dependently increased CVP and Pplat and decreased CO. LPS-induced peritonitis decreased myocardial function ex vivo but MV attenuated systolic dysfunction Vt-dependently. Cardiac endothelial VCAM-1 expression was increased by LPS treatment independent of MV. Cardiac edema was lowered Vt-dependently by MV, particularly after LPS, and correlated inversely with systolic myocardial function parameters ex vivo. Conclusion MV attenuated LPS-induced systolic myocardial dysfunction in a Vt-dependent manner. This was associated with a reduction in cardiac edema following a lower transmural coronary venous outflow pressure during LPS-induced coronary inflammation.

  18. Flocculation and floc break-up related to tidally induced turbulent shear in a low-turbidity, microtidal estuary

    DEFF Research Database (Denmark)

    Markussen, Thor Nygaard; Andersen, Thorbjørn Joest

    2014-01-01

    Flocculation and floc break-up dynamics were studied in two field campaigns with calm winds in the northernmost part of the Danish Wadden Sea. The studies were carried out using a LISST-100C together with CTD-instruments and a current meter. A quasi-Lagrangian profiling method was used to assess...... flocculation and floc break-up dynamics in the lower part of the water column in the period around slack water. These dynamics were confirmed in the Eulerian deployments and were reoccurring in every tidal cycle. The dynamics were mostly governed by changes in turbulent shear. Strong microflocs with a lower...... mean threshold diameter of 50–60 μm present at high turbulent shear flocculated to form fragile macroflocs with sizes of several hundred microns and mean diameters above 80 μm around slack water periods. A hysteresis in floc break-up and flocculation was found at high water slack (HWS), as flocs formed...

  19. Tidal Evolution of Asteroidal Binaries. Ruled by Viscosity. Ignorant of Rigidity

    CERN Document Server

    Efroimsky, Michael

    2015-01-01

    The rate of tidal evolution of asteroidal binaries is defined by the dynamical Love numbers divided by quality factors. Common is the (often illegitimate) approximation of the dynamical Love numbers with their static counterparts. As the static Love numbers are, approximately, proportional to the inverse rigidity, this renders a popular fallacy that the tidal evolution rate is determined by the product of the rigidity by the quality factor: $\\,k_l/Q\\propto 1/(\\mu Q)\\,$. In reality, the dynamical Love numbers depend on the tidal frequency and all rheological parameters of the tidally perturbed body (not just rigidity). We demonstrate that in asteroidal binaries the rigidity of their components plays virtually no role in tidal friction and tidal lagging, and thereby has almost no influence on the intensity of tidal interactions (tidal torques, tidal dissipation, tidally induced changes of the orbit). A key quantity that determines the tidal evolution is a product of the effective viscosity $\\,\\eta\\,$ by the tid...

  20. Molecular and structural analyses of a novel temperature stress-induced lipocalin from wheat and Arabidopsis.

    Science.gov (United States)

    Frenette Charron, Jean Benoit; Breton, Ghislain; Badawi, Mohamed; Sarhan, Fathey

    2002-04-24

    Two cDNAs corresponding to a novel lipocalin were identified from wheat and Arabidopsis. The two cDNAs designated Tatil for Triticum aestivum L. temperature-induced lipocalin and Attil for Arabidopsis thaliana temperature-induced lipocalin encode polypeptides of 190 and 186 amino acids respectively. Structure analyses indicated the presence of the three structurally conserved regions that characterize lipocalins. Sequence analyses revealed that this novel class of plant lipocalin shares homology with three evolutionarily related lipocalins: the mammalian apolipoprotein D (ApoD), the bacterial lipocalin and the insect Lazarillo. The comparison of the putative tertiary structures of both the human ApoD and the wheat TaTIL suggest that the two proteins differ in membrane attachment and ligand interaction. Northern analyses demonstrated that Tatil and Attil transcripts are upregulated during cold acclimation and heat-shock treatment. The putative functions of this novel class of plant lipocalins during temperature stresses are discussed.

  1. Stuttering, induced fluency, and natural fluency: a hierarchical series of activation likelihood estimation meta-analyses.

    Science.gov (United States)

    Budde, Kristin S; Barron, Daniel S; Fox, Peter T

    2014-12-01

    Developmental stuttering is a speech disorder most likely due to a heritable form of developmental dysmyelination impairing the function of the speech-motor system. Speech-induced brain-activation patterns in persons who stutter (PWS) are anomalous in various ways; the consistency of these aberrant patterns is a matter of ongoing debate. Here, we present a hierarchical series of coordinate-based meta-analyses addressing this issue. Two tiers of meta-analyses were performed on a 17-paper dataset (202 PWS; 167 fluent controls). Four large-scale (top-tier) meta-analyses were performed, two for each subject group (PWS and controls). These analyses robustly confirmed the regional effects previously postulated as "neural signatures of stuttering" (Brown, Ingham, Ingham, Laird, & Fox, 2005) and extended this designation to additional regions. Two smaller-scale (lower-tier) meta-analyses refined the interpretation of the large-scale analyses: (1) a between-group contrast targeting differences between PWS and controls (stuttering trait); and (2) a within-group contrast (PWS only) of stuttering with induced fluency (stuttering state).

  2. Analysis of 19-year tidal data

    Institute of Scientific and Technical Information of China (English)

    黄祖珂; 陈宗镛; 司鸿业; 叶琳

    1997-01-01

    19-year tidal data of the 3 stations, Huludao, Qinhuangdao and Kanmen, have totally been analysed, and the amplitudes and phases of 472 tidal constituents have been calculated with a resolution of Δ≥ 0.002 2 /h. Based on the draconitic tide, the anomalistic tide and pole tide obtained, the ultra-long-period variations of the mean sea level have been predicted. The annual tidal analysis of 19-year data at the above-mentioned stations and at Tanggu, Longkou has been carried out. The stability of the annual tidal analysis has been investigated with regard to the astronomical factors, the nonlinear effects and the variations of sea-bottom topography.

  3. Biogeomorphology of tidal landforms: physical and biological processes shaping the tidal landscape

    Science.gov (United States)

    Marani, M.; D'Alpaos, A.; Da Lio, C.

    2011-12-01

    The equilibrium states and transient dynamics of tidal landforms are the result of many concurring physical and biological forcings, such as tidal range, wind climate, sediment supply, vegetation and microphytobenthos development, and rates of relative sea level rise (RSLR). A 0D model of the coupled elevation-vegetation dynamics is used to explore the relative role of the physical and biological factors shaping these systems. We find that salt marshes exposed to large tidal ranges are more stable, and therefore more resilient to increasing rates of RSLR, than marshes subjected to low tidal ranges and that subtidal platforms in macrotidal systems are less exposed to wind-induced erosion processes than their counterparts in systems with smaller tidal fluctuations. Notably, we find that vegetation crucially affects both the equilibrium marsh elevation, through dissipation of wind waves and organic accumulation, and marsh resilience to accelerations in RSLR rates, important differences being associated with different vegetation types. Furthermore, our results show that the existence and stability of equilibrium states fundamentally depend on the local wind and tidal regime, even within the same tidal system. Finally, we propose a modelling framework to study how biological evolution lead to the emergence of tidal landforms as we know them.

  4. The origin of type-I profiles in cluster lenticulars: An interplay between ram pressure stripping and tidally-induced spiral migration

    CERN Document Server

    Clarke, Adam J; Roškar, Rok; Quinn, and Tom

    2016-01-01

    Using $N$-body+SPH simulations of galaxies falling into a cluster, we study the evolution of their radial density profiles. When evolved in isolation, galaxies develop a type~II (down-bending) profile. In the cluster, the evolution of the profile depends on the minimum cluster-centric radius the galaxy reaches, which controls the degree of ram pressure stripping. If the galaxy falls to $\\sim 50\\%$ of the virial radius, then the profile remains type~II, but if the galaxy reaches down to $\\sim 20\\%$ of the virial radius the break weakens and the profile becomes more type~I like. The velocity dispersions are only slightly increased in the cluster simulations compared with the isolated galaxy; random motion therefore cannot be responsible for redistributing material sufficiently to cause the change in the profile type. Instead we find that the joint action of radial migration driven by tidally-induced spirals and the outside-in quenching of star formation due to ram pressure stripping alters the density profile. ...

  5. Tidal river dynamics

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Jay, D.A.

    2016-01-01

    Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology. It is only in the last few decades that substantial research efforts have been focused on the interactions of river discharge with tidal waves and storm surges into regions beyond the limit of salinity

  6. Cosmic Tidal Reconstruction

    CERN Document Server

    Zhu, Hong-Ming; Yu, Yu; Er, Xinzhong; Chen, Xuelei

    2015-01-01

    The gravitational coupling of a long wavelength tidal field with small scale density fluctuations leads to anisotropic distortions of the locally measured small scale matter correlation function. Since the local correlation function is statistically isotropic in the absence of such tidal interactions, the tidal distortions can be used to reconstruct the long wavelength tidal field and large scale density field in analogy with the cosmic microwave background lensing reconstruction. In this paper we present in detail a formalism for the cosmic tidal reconstruction and test the reconstruction in numerical simulations. We find that the density field on large scales can be reconstructed with good accuracy and the cross correlation coefficient between the reconstructed density field and the original density field is greater than 0.9 on large scales ($k\\lesssim0.1h/\\mathrm{Mpc}$). This is useful in the 21cm intensity mapping survey, where the long wavelength radial modes are lost due to foreground subtraction proces...

  7. The effect of beach slope on tidal influenced saltwater intrusion

    Science.gov (United States)

    Zhao, Z.; Shen, C.; Jin, G.; Xin, P.; Hua, G.; Tao, X.; Zhao, J.

    2015-12-01

    Beach slope changes the tidal induced saltwater-freshwater circulations in coastal aquifers. However, the effect of beach slope on tidal influenced saltwater-freshwater mixing process is far from understood. Based on sand flume experiments and numerical simulations, we investigated the intrusion process of saltwater into freshwater under tidal forcing and variable beach slopes. The sand flume experiment results show that milder slope induces larger upper saline plume (USP) and seaward salt wedge interface (SWI) under tidal forcing. While, the steady state SWI keeps stagnant with different beach slopes. Consistent with the previous research, our numerical simulations also show a lager flux exchange across the milder beach induced by the tidal fluctuations. The groundwater table fluctuates more intensify with deeper beach slope. The next step of our study will pay attention to the effect of beach slope on the instability of USP which induces the salt-fingering flow.

  8. Integral analyses of fission product retention at mitigated thermally-induced SGTR using ARTIST experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Rýdl, Adolf, E-mail: adolf.rydl@psi.ch; Lind, Terttaliisa, E-mail: terttaliisa.lind@psi.ch; Birchley, Jonathan, E-mail: jonathan.birchley@psi.ch

    2016-02-15

    Highlights: • Source term analyses in a PWR of mitigated thermally-induced SGTR scenario performed. • Experimental ARTIST program results on aerosol scrubbing efficiency used in analyses. • Results demonstrate enhanced aerosol retention in a flooded steam generator. • High aerosol retention cannot be predicted by current theoretical scrubbing models. - Abstract: Integral source-term analyses are performed using MELCOR for a PWR Station Blackout (SBO) sequence leading to induced steam generator tube rupture (SGTR). In the absence of any mitigation measures, such a sequence can result in a containment bypass where the radioactive materials can be released directly to the environment. In some SGTR scenarios flooding of the faulted SG secondary side with water can mitigate the accident escalation and also the release of aerosol-borne and volatile radioactive materials. Data on the efficiency of aerosol scrubbing in an SG tube bundle were obtained in the international ARTIST project. In this paper ARTIST data are used directly with parametric MELCOR analyses of a mitigated SGTR sequence to provide more realistic estimates of the releases to environment in such a type of scenario or similar. Comparison is made with predictions using the default scrubbing model in MELCOR, as a representative of the aerosol scrubbing models in current integral codes. Specifically, simulations are performed for an unmitigated sequence and 2 cases where the SG secondary was refilled at different times after the tube rupture. The results, reflecting the experimental observations from ARTIST, demonstrate enhanced aerosol retention in the highly turbulent two-phase flow conditions caused by the complex geometry of the SG secondary side. This effect is not captured by any of the models currently available. The underlying physics remains only partly understood, indicating need for further studies to support a more mechanistic treatment of the retention process.

  9. Investigation on Tidal Components in GPS Coordinates

    Science.gov (United States)

    Araszkiewicz, Andrzej; Bogusz, Janusz; Figurski, Mariusz

    2009-01-01

    This paper presents analyses on the GPS coordinates from sub-diurnal solutions of EPN data provided by Warsaw Military University of Technology. The aim of this research is to investigate the way the tidal models used in Bernese software (solid Earth and ocean tides as well) fit to the individual conditions of EPN stations. The 1-hour solution technique of GPS data processing was utilized to obtain coordinates of above 70 EPN stations. Additionally several Polish permanent sites with clearly seen oscillations were examined. This processing technique allowed us to recognize diurnal and sub-diurnal residual oscillations which could be next utilized for validation of the tidal models.

  10. Tidal and subtidal hydrodynamics and energetics in a constricted estuary

    Science.gov (United States)

    Zarzuelo, Carmen; López-Ruiz, Alejandro; Díez-Minguito, Manuel; Ortega-Sánchez, Miguel

    2017-02-01

    The dynamics of coastal plain estuaries are mainly associated with variable tidal forcing and local winds in combination with bathymetric complexity and coastline irregularity. Specific features, such as constricted areas, can potentially affect and energize the hydrodynamics of these types of systems. Particularly, tidal range and tidal currents can be significantly amplified where the incoming tidal wave becomes constricted. In this work, the impact of a narrow constriction on a mesotidal estuary was analysed at tidal and subtidal time scales. Tidal hydrodynamics, energy fluxes and energy dissipation were determined for the entire Cádiz Bay (southwestern Spain) using the Delft3D numerical model. Field observations were used to analyse tidal propagation and energy dissipation along the bay constriction and to calibrate and test the numerical model. The results indicate that the presence of the constriction transformed and distorted the tide and increased the tidal range and flow velocities along the channel, with implications on energy dissipation. The tidal currents were oriented along-channel at the central part of the constriction, although abrupt bathymetric changes at the channel inner boundary provoked a sudden rotation of the flow. Although the energy fluxes were higher for spring tides and were strongly influenced by winds, the energy dissipation was controlled by bed shear stresses and vertical dispersion. The significance of this energy dissipation was that it destabilized the water column, which resulted in a weakly stratified system with implications on water quality. At a subtidal scale, the residual water volume exchange was the result of the combined effects of the neap/spring tides, wind and waves, whereas tides were dominant at the tidal scale.

  11. Changing tidal hydrodynamics during different stages of eco-geomorphological development of a tidal marsh: A numerical modeling study

    Science.gov (United States)

    Stark, J.; Meire, P.; Temmerman, S.

    2017-03-01

    The eco-geomorphological development of tidal marshes, from initially low-elevated bare tidal flats up to a high-elevated marsh and its typical network of channels and creeks, induces long-term changes in tidal hydrodynamics in a marsh, which will have feedback effects on the marsh development. We use a two-dimensional hydrodynamic model of the Saeftinghe marsh (Netherlands) to study tidal hydrodynamics, and tidal asymmetry in particular, for model scenarios with different input bathymetries and vegetation coverages that represent different stages of eco-geomorphological marsh development, from a low elevation stage with low vegetation coverage to a high and fully vegetated marsh platform. Tidal asymmetry is quantified along a 4 km marsh channel by (1) the difference in peak flood and peak ebb velocities, (2) the ratio between duration of the rising tide and the falling tide and (3) the time-integrated dimensionless bed shear stress during flood and ebb. Although spatial variations in tidal asymmetry are large and the different indicators for tidal asymmetry do not always respond similarly to eco-geomorphological changes, some general trends can be obtained. Flood-dominance prevails during the initial bare stage of a low-lying tidal flat. Vegetation establishment and platform expansion lead to marsh-scale flow concentration to the bare channels, causing an increase in tidal prism in the channels along with a less flood-dominant asymmetry of the horizontal tide. The decrease in flood-dominance continues as the platform grows vertically and the sediment-demand of the platform decreases. However, when the platform elevation gets sufficiently high in the tidal frame and part of the spring-neap cycle is confined to the channels, the discharge in the channels decreases and tidal asymmetry becomes more flood-dominant again, indicating an infilling of the marsh channels. Furthermore, model results suggest that hydro-morphodynamic feedbacks based on tidal prism to channel

  12. Tidal Love numbers of a slowly-spinning neutron star

    CERN Document Server

    Pani, Paolo; Ferrari, Valeria

    2015-01-01

    By extending our recent framework to describe the tidal deformations of a spinning compact object, we compute for the first time the tidal Love numbers of a spinning neutron star to linear order in the angular momentum. The spin of the object introduces couplings between electric and magnetic distortions and new classes of spin-induced ("rotational") tidal Love numbers emerge. We focus on stationary tidal fields, which induce axisymmetric perturbations. We present the perturbation equations for both electric-led and magnetic-led rotational Love numbers for generic multipoles and explicitly solve them for various tabulated equations of state and for a tidal field with an electric (even parity) and magnetic (odd parity) component with l=2,3,4. For a binary system close to the merger, various components of the tidal field become relevant. In this case we find that an octupolar magnetic tidal field can significantly modify the mass quadrupole moment of a neutron star. Preliminary estimates, assuming a spin parame...

  13. Mean water level setup/setdown in the inlet-lagoon system induced by tidal action-a case study of Xincun Inlet, Hainan Island in China

    Institute of Scientific and Technical Information of China (English)

    GONG Wenping; SHEN Jian; WANG Daoru

    2008-01-01

    With the tides propagating from the open sea to the lagoon, the mean water level (MWL) in the inlet and lagoon becomes different from that at the open sea, and a setup/setdown is generated. The change of MWL (setup/setdown) in the system imposes a great impact on regulating the development of tidal marshes, on determining the long-term water level for harbor maintenance, on the planning for the water front development with the flood control for the possible inundation, and on the interpretation of the historical sea level change when using tidal marsh peat deposits in the lagoon as the indicator for open sea' s sea level. In this ease study on the mechanisms which control the setup/setdown in Xincun Inlet, Hainan in China, the 2-D barotropic mode of Eulerian - Lagrangian CIRCulation (ELCIRC) model was utilized. After model calibration and verification, a series of numerical experiments were conducted to examine the effects of bottom friction and advection terms, wetting and drying of intertidal areas, bathymetry and boundary conditions on the setup/setdown in the system. The modeling results show that setup occurs over the inlet and lagoon areas with an order of one tenth of the tide range at the entrance. The larger the bottom friction is, a larger setup is generated.Without the advection term, the setup is reduced due to a decrease of water level gradient to compensate for the disappearance of the advection term. Even without overtides, a setup can still be developed in the system. Sea level rise and dredging in the inlet and tidal channel can cause a decrease of setup in the system, whereas shoaling of the system can increase the setup. The uniqueness of the Xincun Inlet with respect to MWL change is that there is no evident setdown in the inlet, which can be attributed to the complex geometry and bathymetry associated with the inlet system.

  14. Tidal Evolution of Exoplanets

    CERN Document Server

    Correia, Alexandre C M

    2010-01-01

    Tidal effects arise from differential and inelastic deformation of a planet by a perturbing body. The continuous action of tides modify the rotation of the planet together with its orbit until an equilibrium situation is reached. It is often believed that synchronous motion is the most probable outcome of the tidal evolution process, since synchronous rotation is observed for the majority of the satellites in the Solar System. However, in the 19th century, Schiaparelli also assumed synchronous motion for the rotations of Mercury and Venus, and was later shown to be wrong. Rather, for planets in eccentric orbits synchronous rotation is very unlikely. The rotation period and axial tilt of exoplanets is still unknown, but a large number of planets have been detected close to the parent star and should have evolved to a final equilibrium situation. Therefore, based on the Solar System well studied cases, we can make some predictions for exoplanets. Here we describe in detail the main tidal effects that modify the...

  15. Structural and tidal models of Titan and inferences on cryovolcanism

    OpenAIRE

    Sohl, F.; Solomonidou, A.; Wagner, F.W.; Coustenis, A.; Hussmann, H.; Schulze-Makuch, D.

    2014-01-01

    Titan, Saturn's largest satellite, is subject to solid body tides exerted by Saturn on the timescale of its orbital period. The tide-induced internal redistribution of mass results in tidal stress variations, which could play a major role for Titan's geologic surface record. We construct models of Titan's interior that are consistent with the satellite's mean density, polar moment-of-inertia factor, obliquity, and tidal potential Love number k2 as derived from Cassini observations of Titan's ...

  16. Tidal deformability of dark matter clumps

    CERN Document Server

    Mendes, Raissa F P

    2016-01-01

    We analyze the tidal deformability of a clump of dark matter particles, modelled by the collisionless Boltzmann equation. We adopt a wave-mechanical approach to the problem, in which the dynamical equations are approximated by a set of Schr\\"{o}dinger-Poisson equations, within the limit that the effective de Broglie wavelength is comparable to the spatial variation scale of the particle distribution. We argue that such a treatment allows for a smaller number of coupled differential equations and more accessible perturbative analyses, while keeping the description within the dynamical timescale relatively accurate. Moreover, it provides an approximate mapping between perturbed boson star configurations and dynamical dark matter clumps. We present an analysis of the tidal deformability of a minimally-coupled boson star to illustrate this (approximate) correspondence.

  17. Tidal Energy Research

    Energy Technology Data Exchange (ETDEWEB)

    Stelzenmuller, Nickolas [Univ of Washington; Aliseda, Alberto [Univ of Washington; Palodichuk, Michael [Univ of Washington; Polagye, Brian [Univ of Washington; Thomson, James [Univ of Washington; Chime, Arshiya [Univ of Washington; Malte, Philip [Univ of washington

    2014-03-31

    This technical report contains results on the following topics: 1) Testing and analysis of sub-scale hydro-kinetic turbines in a flume, including the design and fabrication of the instrumented turbines. 2) Field measurements and analysis of the tidal energy resource and at a site in northern Puget Sound, that is being examined for turbine installation. 3) Conceptual design and performance analysis of hydro-kinetic turbines operating at high blockage ratio, for use for power generation and flow control in open channel flows.

  18. Silting in the Lower Courses of Tidal Sluices in China

    Institute of Scientific and Technical Information of China (English)

    张金善; 黄建维; 杨红

    2004-01-01

    Serious sediment deposition often occurs after the construction of tidal sluices in small or medium-sized tidal muddy estuaries, so desilting or dredging is needed to meet the demands of flood discharge, saltwater retaining, and navigation in those areas. In this paper, the problem of sedimeut deposition induced by construction of tidal sluices is analyzed.Different problems of silting near tidal sluices for different types of estuaries are summed up, at the same time, corresponding methods are given to solve these problems, and a few successful examples are also given. The idea of comprehensive regulation and utilization of estuaries is put forward, and some proposals for solution of sediment deposition in this kind of estuaries are made.

  19. ANALYSES OF CHROMOSOME ABERRATIONS IN LYMPHOCYTES AND BONE MARROW CELLS INDUCED BY RADIATION OR BENZENE

    Institute of Scientific and Technical Information of China (English)

    张鸿源; 王兰金; 等

    1995-01-01

    The chromosomoe and chromatid type aberration can be induced by benzene and the dicentric and ring ones were not observed in vitro experiment but observed in vivo one.In vitro experiment a good linear reression can be given between benzene concentrations and total aberration cells while power regression for radiation dose.The chromosome aberrations induced by benzene combined with radiation in rabbit blood lymphocytes are higher than in bone marryow cells.

  20. Magnetic field evolution in tidal disruption events

    CERN Document Server

    Bonnerot, Clément; Lodato, Giuseppe; Rossi, Elena M

    2016-01-01

    When a star gets tidally disrupted by a supermassive black hole, its magnetic field is expected to be transmitted to the debris. In this paper, we study this process via smoothed particle magnetohydrodynamical simulations of the disruption and early debris evolution including the stellar magnetic field. As the gas stretches into a stream, we show that the magnetic field evolution is strongly dependent on its orientation with respect to the stretching direction. In particular, an alignment of the field lines with the direction of stretching induces an increase of the magnetic energy. For disruptions happening well within the tidal radius, the star compression causes the magnetic field strength to sharply increase by an order of magnitude at the time of pericentre passage. If the disruption is partial, we find evidence for a dynamo process occurring inside the surviving core due to the formation of vortices. This causes an amplification of the magnetic field strength by a factor of $\\sim 10$. However, this valu...

  1. Preventive intervention possibilities in radiotherapy- and chemotherapy-induced oral mucositis : Results of meta-analyses

    NARCIS (Netherlands)

    Stokman, M A; Spijkervet, F K L; Boezen, H M; Schouten, J.P.; Roodenburg, J L N; de Vries, E G E

    2006-01-01

    The aim of these meta-analyses was to evaluate the effectiveness of interventions for the prevention of oral mucositis in cancer patients treated with head and neck radiotherapy and/or chemotherapy, with a focus on randomized clinical trials. A literature search was performed for reports of randomiz

  2. Proteomic Analyses of Cellular Events Mediating/Inhibiting Chemical-Induced Injury

    Science.gov (United States)

    2009-07-21

    Yan L, Wang X, Pei R, Van T, Zhao Y, Guo X: Cytotoxicity of carbon nanomaterials: single-wall nanotube , multi·wall nanotube , and fullerene. Environ...data and functional analyses. 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF...post-formalin exposure. rat lungs were removed and frozen for 2-DE. 2.1.2 Lung Function Test Lung function in replicate rats was characterized as

  3. Analyses on Radiation Effects in Solid Amino Acids Induced by Low Energy Fe~+ Ion Beams

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Radiation effects in Solid samples of L(+)-cysteine and L(+)-cysteine hydroehloride monohydrate induced by 110 keV Fe~+ion implantation were characterized with FTIR, ESR,HPLC and ESI-FTMS.It was validated that solid samples of the irradiated amino acids were damaged to a certain extent,and some new groups or molecular products formed.

  4. Gene expression array analyses predict increased proto-oncogene expression in MMTV induced mammary tumors.

    Science.gov (United States)

    Popken-Harris, Pamela; Kirchhof, Nicole; Harrison, Ben; Harris, Lester F

    2006-08-01

    Exogenous infection by milk-borne mouse mammary tumor viruses (MMTV) typically induce mouse mammary tumors in genetically susceptible mice at a rate of 90-95% by 1 year of age. In contrast to other transforming retroviruses, MMTV acts as an insertional mutagen and under the influence of steroid hormones induces oncogenic transformation after insertion into the host genome. As these events correspond with increases in adjacent proto-oncogene transcription, we used expression array profiling to determine which commonly associated MMTV insertion site proto-oncogenes were transcriptionally active in MMTV induced mouse mammary tumors. To verify our gene expression array results we developed real-time quantitative RT-PCR assays for the common MMTV insertion site genes found in RIII/Sa mice (int-1/wnt-1, int-2/fgf-3, int-3/Notch 4, and fgf8/AIGF) as well as two genes that were consistently up regulated (CCND1, and MAT-8) and two genes that were consistently down regulated (FN1 and MAT-8) in the MMTV induced tumors as compared to normal mammary gland. Finally, each tumor was also examined histopathologically. Our expression array findings support a model whereby just one or a few common MMTV insertions into the host genome sets up a dominant cascade of events that leave a characteristic molecular signature.

  5. Quantitative Proteomic Analyses of Molecular Mechanisms Associated with Cytoplasmic Incompatibility in Drosophila melanogaster Induced by Wolbachia.

    Science.gov (United States)

    Yuan, Lin-Ling; Chen, Xiulan; Zong, Qiong; Zhao, Ting; Wang, Jia-Lin; Zheng, Ya; Zhang, Ming; Wang, Zailong; Brownlie, Jeremy C; Yang, Fuquan; Wang, Yu-Feng

    2015-09-04

    To investigate the molecular mechanisms of cytoplasmic incompatibility (CI) induced by Wolbachia bacteria in Drosophila melanogaster, we applied an isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomic assay to identify differentially expressed proteins extracted from spermathecae and seminal receptacles (SSR) of uninfected females mated with either 1-day-old Wolbachia-uninfected (1T) or infected males (1W) or 5-day-old infected males (5W). In total, 1317 proteins were quantified; 83 proteins were identified as having at least a 1.5-fold change in expression when 1W was compared with 1T. Differentially expressed proteins were related to metabolism, immunity, and reproduction. Wolbachia changed the expression of seminal fluid proteins (Sfps). Wolbachia may disrupt the abundance of proteins in SSR by affecting ubiquitin-proteasome-mediated proteolysis. Knocking down two Sfp genes (CG9334 and CG2668) in Wolbachia-free males resulted in significantly lower embryonic hatch rates with a phenotype of chromatin bridges. Wolbachia-infected females may rescue the hatch rates. This suggests that the changed expression of some Sfps may be one of the mechanisms of CI induced by Wolbachia. This study provides a panel of candidate proteins that may be involved in the interaction between Wolbachia and their insect hosts and, through future functional studies, may help to elucidate the underlying mechanisms of Wolbachia-induced CI.

  6. Consideration of tidal influences in determining measurement periods when monitoring built-environment radon levels

    Energy Technology Data Exchange (ETDEWEB)

    Crockett, R.G.M.; Phillips, P.S. [Northampton Univ., School of Applied Sciences (United Kingdom); Gillmore, G.K. [Bradford Univ., School of Archaeological, Geographical and Environmental Sciences (United Kingdom); Denman, A.R.; Groves-Kirkby, C.J. [Northampton General Hospital, Medical Physics Dept. (United Kingdom)

    2006-07-01

    Using three hourly-sampling continuous radon monitors, deployed at separate locations in and around the town of Northampton, UK, during the period May 2002 to September 2005, evidence has been identified of tidal influences on built environment radon levels. The data-sets from these deployments, together with additional data-sets collected from a house in Devon, UK, over the period May 1994 to October 1996, and made available by the UK Building Research Establishment, have been analysed using a number of analytical techniques, including a novel cortion technique developed during the investigation. Radon concentration levels in all of the investigated sites exhibit cyclic variation with a period of approximately 14-15 days, equivalent to the spring-tide interval, and lag the corresponding new and full moons by varying periods. The tide/radon lag interval for the two public-sector buildings changes abruptly in September/October, indicating that a significant characteristic of these buildings changes at this time. For domestic properties, the lag is relatively unchanged during the year, but is greater in Devon, in the South-West of England, than in Northampton, in the English East Midlands. These differences are attributed to location relative to coastlines (the South-West experiences greater tidal-loading than the Midlands), underlying geology and rock/soil hydration. Depending on its position within the local 14 to 15-day tidally-induced radon cycle, an individual 7-day radon measurement may yield an erroneous estimate of longer term average levels, up to 46% higher or lower than the average level for one of the reported data-sets. Thus a building with a mean radon concentration below the local Action Level could appear to be unsafe if measured around a tidal-cyclic radon maximum: conversely, a building with a mean radon concentration above the Action Level could appear to be safe when measured around a tidal-cyclic radon minimum. A minimum radon-measurement period

  7. LES of Langmuir supercells under constant crosswind tidal forcing

    Science.gov (United States)

    Walker, Rachel; Zhang, Jie; Juha, Mario; Gosch, Chester; Tejada-Martinez, Andres

    2015-11-01

    We report on the impact of a crosswind tidal current on Langmuir supercells (LSCs) in shallow water computed via LES. LSCs consist of parallel counter rotating vortices engulfing the water column in unstratified conditions. These cells have been observed in shallow continental shelf regions of ~15 meters depth during the passage of storms. The cells are aligned roughly in the wind direction and are generated by the interaction of the wind-driven shear current with the Stokes drift velocity induced by surface gravity waves. Without tides, LES reveals that the typical crosswind width of a LSC is ~4 times the water column depth (H). Under a relatively weak crosswind tidal current (weaker than the downwind current), the constant crosswind tidal forcing applied causes a merging of cells leading to cells of width ~8H. The opposite occurs under a crosswind tidal current stronger than the downwind current as the constant crosswind tidal force is able to break up the LSCs giving rise to smaller scale cells with different turbulent structure than that associated with LSC. Statistics of the turbulence during strong and weak crosswind tides will be contrasted and implications of an oscillating crosswind tidal force will be discussed. Support from the US National Science Foundation and the Gulf of Mexico Research Initiative is gratefully acknowledged.

  8. Dynamical Tidal Response of a Rotating Neutron Star

    Science.gov (United States)

    Landry, Philippe; Poisson, Eric

    2017-01-01

    The gravitational wave phase of a neutron star (NS) binary is sensitive to the deformation of the NS that results from its companion's tidal influence. In a perturbative treatment, the tidal deformation can be characterized by a set of dimensionless constants, called Love numbers, which depend on the NS equation of state. For static NSs, one type of Love number encodes the response to gravitoelectric tidal fields (associated with mass multipole moments), while another does likewise for gravitomagnetic fields (associated with mass currents). A NS subject to a gravitomagnetic tidal field develops internal fluid motions through gravitomagnetic induction; the fluid motions are irrotational, provided the star is non-rotating. When the NS is allowed to rotate, the situation is complicated by couplings between the tidal field and the star's spin. The problem becomes tractable in the slow-rotation limit. In this case, the fluid motions induced by an external gravitomagnetic field are fully dynamical, even if the tidal field is stationary: interior metric and fluid variables are time-dependent, and vary on the timescale of the rotation period. Remarkably, the exterior geometry of the NS remains time-independent.

  9. Numerical analyses of a water pool under loadings caused by a condensation induced water hammer

    Energy Technology Data Exchange (ETDEWEB)

    Timperi, A.; Paettikangas, T.; Calonius, K.; Tuunanen, J.; Poikolainen, J.; Saarenheimo, A. [VTT Industrial Systems (Finland)

    2004-03-01

    Three-dimensional simulations of a rapidly condensing steam bubble in a water pool have been performed by using the commercial computational fluid dynamics (CFD) code Star-CD. The condensing bubble was modelled by using a mass sink in a single-phase calculation. The pressure load on the wall of the pool was determined and transferred to the structural analyses code ABAQUS. The analyses were done for a test pool at Lappeenranta University of Technology. The structural integrity of the pool during steam experiments was investigated by assuming as a test load the rapid condensation of a steam bubble with a diameter of 20 cm. The mass sink for modelling the collapse of the bubble was deter-mined from the potential theory of incompressible fluid. The rapid condensation of the bubble within 25 ms initiated a strong condensation water hammer. The maximum amplitude of the pressure load on the pool wall was approximately 300 kPa. The loads caused by the high compression waves lasted only about 0.4 ms. The loadings caused by larger bubbles or more rapid collapse could not be calculated with the present method. (au)

  10. The tidal signal in inverted echo-sounder records

    Science.gov (United States)

    Cartwright, D. E.

    1982-06-01

    Four IES records of several months duration from the western equatorial Atlantic are analysed with principal interest in their tidal content. Spectral noise level in the tidal bands is some two orders of magnitude higher than in comparable sea-level records, but the main constituents of both diurnal and semi-diurnal tides stand out with usable coherence with the tidal potential. A mid-ocean record, FLAVIA, gives amplitudes and phases that correspond closely with the surface tide, but three other records in a region of disturbed bathymetry near the continental shelf give amplitudes and phases which differ from the expected surface effect, indicating relatively strong coherent internal tides in the region as well as an evident incoherent tidal signal. Two of the latter records also show second-harmonic distortion, which is characteristic of internal tides, in the present case corresponding to a steeppened forward face of the internal wave. Theory, following the analysis of LONG (1972 Tellus, 24, 88-89), suggests that this form of wave steepening is due to the steady shear in the surface layer. The physical theory of acoustic time-delay in vertical transmission through long internal waves with and without surface elevation is analysed quantitatively. In the region studied a pure internal tide of amplitude 10 m at 200-m depth would produce the observed changes in tidal signal. Wave amplitudes resulting from tidal flow over a 2.4-km high ridge, computed from the linear theory of ZEILON (1912 Kungliga Svenska Vetenskapsakademiens Handligar, 47, 1-45), are only about 1.2 m maximum, but the theory does suggest a likely mechanism for producing coherent internal tidal motion, possibly by invoking the shelf edge.

  11. Regional tidal lung strain in mechanically ventilated normal lungs.

    Science.gov (United States)

    Paula, Luis Felipe; Wellman, Tyler J; Winkler, Tilo; Spieth, Peter M; Güldner, Andreas; Venegas, Jose G; Gama de Abreu, Marcelo; Carvalho, Alysson R; Vidal Melo, Marcos F

    2016-12-01

    Parenchymal strain is a key determinant of lung injury produced by mechanical ventilation. However, imaging estimates of volumetric tidal strain (ε = regional tidal volume/reference volume) present substantial conceptual differences in reference volume computation and consideration of tidally recruited lung. We compared current and new methods to estimate tidal volumetric strains with computed tomography, and quantified the effect of tidal volume (VT) and positive end-expiratory pressure (PEEP) on strain estimates. Eight supine pigs were ventilated with VT = 6 and 12 ml/kg and PEEP = 0, 6, and 12 cmH2O. End-expiratory and end-inspiratory scans were analyzed in eight regions of interest along the ventral-dorsal axis. Regional reference volumes were computed at end-expiration (with/without correction of regional VT for intratidal recruitment) and at resting lung volume (PEEP = 0) corrected for intratidal and PEEP-derived recruitment. All strain estimates demonstrated vertical heterogeneity with the largest tidal strains in middependent regions (P < 0.01). Maximal strains for distinct estimates occurred at different lung regions and were differently affected by VT-PEEP conditions. Values consistent with lung injury and inflammation were reached regionally, even when global measurements were below critical levels. Strains increased with VT and were larger in middependent than in nondependent lung regions. PEEP reduced tidal-strain estimates referenced to end-expiratory lung volumes, although it did not affect strains referenced to resting lung volume. These estimates of tidal strains in normal lungs point to middependent lung regions as those at risk for ventilator-induced lung injury. The different conditions and topography at which maximal strain estimates occur allow for testing the importance of each estimate for lung injury.

  12. Molecular cloning and functional analyses of low-temperature induced genes from Ammopiptanthus mongolicus

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Studies on the cold-responsive genes and cold signaling of woody species drop far behind in comparison to herbaceous plants.Due to similar lignified structure,perennial characteristic,and enhanced tolerance,it seems much easier to find strongly antifreeze genes and obtain effective results in transgenic woody plants.In this study,Ammopiptanthus mongolicus,an evergreen,broadleaf and cold-resist leguminous shrub growing in the desert of Inner Mongolia,was used as a material for low-temperature induced gene is...

  13. Paleoecological Perspectives on Tidal Marsh Degradation at Elkhorn Slough, California

    Science.gov (United States)

    Watson, E. B.; Wasson, K.; Woolfolk, A.; van Dyke, E.

    2007-05-01

    Elkhorn Slough is the second largest area of estuarine tidal wetlands in California, and one of the first U.S. estuarine sanctuaries. Region-wide, 90% of historic tidal wetlands have been lost or restricted from tidal flow due to diking for agricultural use, salt pond construction, and development. However, wetland loss at Elkhorn Slough is currently being driven largely by tidal erosion, and the subsequent expansion of tidal channels and shoreline recession. This study reports on the use of paleoecological analyses to support and inform current restoration and conservation activities at Elkhorn Slough. Analyses of three sediment cores for fossil pollen, organic content, accretion rates, and the removal and stratigraphic description of twelve additional cores have established the timing of marsh establishment, current and prehistoric estuarine salinity, wetland plant abundance and distributions, and the relative contributions of mineral and organic sediment to wetland sediment accumulation. By understanding prehistoric processes and conditions and past variability more thoroughly, managers will be able to evaluate conservation, restoration, and management alternatives in a more informed fashion.

  14. Compositional and micro-scratch analyses of laser induced colored surface of titanium

    Science.gov (United States)

    Akman, Erhan; Cerkezoglu, Ecem

    2016-09-01

    Laser marking of metallic surface is a very important application for industry. It is revealed that controlled oxide layer generation above the treated surface leads to colored appearance of metals with interference effect. The oxide layer control is provided with laser and process parameters. In this study, different colors of the Grade 2 titanium samples have been obtained by varying the laser scanning speed. Chromaticity coordinates of the different color surface have been calculated from the reflectance spectrum of the samples. Compositional analyses have been performed using X-ray photoelectron spectroscopy and X-ray diffraction methods. To examine the mechanical properties of the surface, micro-scratch test has been applied to all the colored surfaces. Although delamination has been observed between two laser scanning speed as 950 mm/s and 450 mm/s, it can be said that the adhesion between the titanium substrate and the oxide coating is good.

  15. Enceladus' tidal dissipation revisited

    Science.gov (United States)

    Tobie, Gabriel; Behounkova, Marie; Choblet, Gael; Cadek, Ondrej; Soucek, Ondrej

    2016-10-01

    A series of chemical and physical evidence indicates that the intense activity at Enceladus' South Pole is related to a subsurface salty water reservoir underneath the tectonically active ice shell. The detection of a significant libration implies that this water reservoir is global and that the average ice shell thickness is about 20-25km (Thomas et al. 2016). The interpretation of gravity and topography data further predicts large variations in ice shell thickness, resulting in a shell potentially thinner than 5 km in the South Polar Terrain (SPT) (Cadek et al. 2016). Such an ice shell structure requires a very strong heat source in the interior, with a focusing mechanism at the SPT. Thermal diffusion through the ice shell implies that at least 25-30 GW is lost into space by passive diffusion, implying a very efficient dissipation mechanism in Enceladus' interior to maintain such an ocean/ice configuration thermally stable.In order to determine in which conditions such a large dissipation power may be generated, we model the tidal response of Enceladus including variable ice shell thickness. For the rock core, we consider a wide range of rheological parameters representative of water-saturated porous rock materials. We demonstrate that the thinning toward the South Pole leads to a strong increase in heat production in the ice shell, with a optimal thickness obtained between 1.5 and 3 km, depending on the assumed ice viscosity. Our results imply that the heat production in the ice shell within the SPT may be sufficient to counterbalance the heat loss by diffusion and to power eruption activity. However, outside the SPT, a strong dissipation in the porous core is required to counterbalance the diffusive heat loss. We show that about 20 GW can be generated in the core, for an effective viscosity of 1012 Pa.s, which is comparable to the effective viscosity estimated in water-saturated glacial tills on Earth. We will discuss the implications of this revisited tidal

  16. Tidal disruption of inviscid planetesimals

    Science.gov (United States)

    Boss, A. P.; Cameron, A. G. W.; Benz, W.

    1991-01-01

    In view of previous efforts' demonstration that strongly dissipative planetesimals are immune to tidal disruption, an examination is presently conducted of the complementary case of inviscid planetesimals arising from collisions that are sufficiently energetic to entirely melt the resulting planetesimal and debris. The tidal disruption is numerically simulated by means of the smoothed particle hydrodynamics (SPH) code of Cameron and Benz (1991), concentrating on the tidal disruption of 0.01 earth-mass planetesimals passing by the earth with variations in the impact parameter at perigee and velocity at infinity. The SPH models show that tidal forces during a close encounter can efficiently convert orbital angular momentum into spin angular momentum, thereby initiating equatorial mass-shedding to inviscid planetesimals that have been spun up beyond the limit of rotational stability.

  17. Tidal Creek Sentinel Habitat Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Ecological Research, Assessment and Prediction's Tidal Creeks: Sentinel Habitat Database was developed to support the National Oceanic and Atmospheric...

  18. On the determination of net bedload transport patters in a natural tidal inlet system (Knudedyb in the Danish Wadden Sea)

    Science.gov (United States)

    Ernstsen, V. B.; Lefebvre, A.; Bartholdy, J.; Bartholomä, A.; Winter, C.

    2012-04-01

    An airborne swath topography survey using a LIDAR (Laser Induced Detection And Ranging or Light Detection And Ranging) system and a ship borne swath bathymetry survey using a multibeam echosounder (MBES) system were carried out within a 100 km2 quadratic section of the natural tidal inlet system Knudedyb in the Danish Wadden Sea. On the basis of the LIDAR data a detailed (0.5 m grid cell size) digital elevation model (DEM) of the dry-lying areas around low water (with the intertidal flats being of primary concern) was generated; whereas the MBES data were used to generate a detailed (also 0.5 m grid cell size) DEM of the tidal inlet main channel. The spatial distribution and characteristics of bedforms in a coastal system potentially yield information on the net bedload transport patterns in the system. The sandy main channel and intertidal flats of the Knudedyb tidal inlet are covered by bedforms. Bedform characterisation using a random field statistical approach (2D spectral analysis, cf. Lefebvre et al. 2011) as well as a discrete approach, in which the geometric variables of individual bedforms are determined (cf. Ernstsen et al. 2010), will be applied to the high-resolution DEMs. Based on these analyses net bedload transport patterns in the Knudedyb tidal inlet system will be determined. The findings will be used to investigate a potential exchange of sand between the main tidal channel and the adjacent intertidal flats. Acknowledgements This work is funded by the Danish Council for Independent Research | Natural Sciences (grant 10-081102) and the German Research Foundation DFG-Research Center / Excellence Cluster "The Ocean in the Earth System".

  19. Back-Analyses of Landfill Instability Induced by High Water Level: Case Study of Shenzhen Landfill

    Directory of Open Access Journals (Sweden)

    Ren Peng

    2016-01-01

    Full Text Available In June 2008, the Shenzhen landfill slope failed. This case is used as an example to study the deformation characteristics and failure mode of a slope induced by high water levels. An integrated monitoring system, including water level gauges, electronic total stations, and inclinometers, was used to monitor the slope failure process. The field measurements suggest that the landfill landslide was caused by a deep slip along the weak interface of the composite liner system at the base of the landfill. The high water level is considered to be the main factor that caused this failure. To calculate the relative interface shear displacements in the geosynthetic multilayer liner system, a series of numerical direct shear tests were carried out. Based on the numerical results, the composite lining system simplified and the centrifuge modeling technique was used to quantitatively evaluate the effect of water levels on landfill instability.

  20. Intestinal microbiome analyses identify melanoma patients at risk for checkpoint-blockade-induced colitis.

    Science.gov (United States)

    Dubin, Krista; Callahan, Margaret K; Ren, Boyu; Khanin, Raya; Viale, Agnes; Ling, Lilan; No, Daniel; Gobourne, Asia; Littmann, Eric; Huttenhower, Curtis; Pamer, Eric G; Wolchok, Jedd D

    2016-02-02

    The composition of the intestinal microbiota influences the development of inflammatory disorders. However, associating inflammatory diseases with specific microbial members of the microbiota is challenging, because clinically detectable inflammation and its treatment can alter the microbiota's composition. Immunologic checkpoint blockade with ipilimumab, a monoclonal antibody that blocks cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) signalling, is associated with new-onset, immune-mediated colitis. Here we conduct a prospective study of patients with metastatic melanoma undergoing ipilimumab treatment and correlate the pre-inflammation faecal microbiota and microbiome composition with subsequent colitis development. We demonstrate that increased representation of bacteria belonging to the Bacteroidetes phylum is correlated with resistance to the development of checkpoint-blockade-induced colitis. Furthermore, a paucity of genetic pathways involved in polyamine transport and B vitamin biosynthesis is associated with an increased risk of colitis. Identification of these biomarkers may enable interventions to reduce the risk of inflammatory complications following cancer immunotherapy.

  1. Field measurements and analyses of environmental vibrations induced by high-speed Maglev.

    Science.gov (United States)

    Li, Guo-Qiang; Wang, Zhi-Lu; Chen, Suwen; Xu, You-Lin

    2016-10-15

    Maglev, offers competitive journey-times compared to the railway and subway systems in markets for which distance between the stations is 100-1600km owing to its high acceleration and speed; however, such systems may have excessive vibration. Field measurements of Maglev train-induced vibrations were therefore performed on the world's first commercial Maglev line in Shanghai, China. Seven test sections along the line were selected according to the operating conditions, covering speeds from 150 to 430km/h. Acceleration responses of bridge pier and nearby ground were measured in three directions and analyzed in both the time and frequency domain. The effects of Maglev train speed on vibrations of the bridge pier and ground were studied in terms of their peak accelerations. Attenuation of ground vibration was investigated up to 30m from the track centerline. Effects of guideway configuration were also analyzed based on the measurements through two different test sections with same train speed of 300km/h. The results showed that peak accelerations exhibited a strong correlation with both train speed and distance off the track. Guideway configuration had a significant effect on transverse vibration, but a weak impact on vertical and longitudinal vibrations of both bridge pier and ground. Statistics indicated that, contrary to the commonly accepted theory and experience, vertical vibration is not always dominant: transverse and longitudinal vibrations should also be considered, particularly near turns in the track. Moreover, measurements of ground vibration induced by traditional high-speed railway train were carried out with the same testing devices in Bengbu in the Anhui Province. Results showed that the Maglev train generates significantly different vibration signatures as compared to the traditional high-speed train. The results obtained from this paper can provide good insights on the impact of Maglev system on the urban environment and the quality of human life

  2. Parametric Dwarf Spheroidal Tidal Interaction

    CERN Document Server

    Fleck, J J; Fleck, Jean-Julien; Kuhn, Jeff R.

    2003-01-01

    The time dependent tidal interaction of the Local Group Dwarf Spheroidal (dS) Galaxies with the Milky Way (MW) can fundamentally affect their dynamical properties. The model developed here extends earlier numerical descriptions of dS-MW tidal interactions. We explore the dynamical evolution of dS systems in circular or elliptical MW orbits in the framework of a parametric oscillator. An analytic model is developed and compared with more general numerical solutions and N-body simulation experiments.

  3. Sensitivity of growth characteristics of tidal sand ridges and long bed waves to formulations of bed shear stress, sand transport and tidal forcing: A numerical model study

    Science.gov (United States)

    Yuan, Bing; de Swart, Huib E.; Panadès, Carles

    2016-09-01

    Tidal sand ridges and long bed waves are large-scale bedforms that are observed on continental shelves. They differ in their wavelength and in their orientation with respect to the principal direction of tidal currents. Previous studies indicate that tidal sand ridges appear in areas where tidal currents are above 0.5 m s-1, while long bed waves occur in regions where the maximum tidal current velocity is slightly above the critical velocity for sand erosion and the current is elliptical. An idealized nonlinear numerical model was developed to improve the understanding of the initial formation of these bedforms. The model governs the feedbacks between tidally forced depth-averaged currents and the sandy bed on the outer shelf. The effects of different formulations of bed shear stress and sand transport, tidal ellipticity and different tidal constituents on the characteristics of these bedforms (growth rate, wavelength, orientation of the preferred bedforms) during their initial formation were examined systematically. The results show that the formulations for bed shear stress and slope-induced sand transport are not critical for the initial formation of these bedforms. For tidal sand ridges, under rectilinear tidal currents, increasing the critical bed shear stress for sand erosion decreases the growth rate and the wavelength of the preferred bedforms significantly, while the orientation angle slightly decreases. The dependence of the growth rate, wavelength and the orientation of the preferred bedforms on the tidal ellipticity is non-monotonic. A decrease in tidal frequency results in preferred bedforms with larger wavelength and smaller orientation angle, while their growth rate hardly changes. In the case of joint diurnal and semidiurnal tides, or spring-neap tides, the characteristics of the bedforms are determined by the dominant tidal constituent. For long bed waves, the number of anticyclonically/cyclonically oriented bedforms with respect to the principal

  4. Extracting sea level residual in tidally dominated estuarine environments

    Science.gov (United States)

    Brown, Jennifer M.; Bolaños, Rodolfo; Howarth, Michael J.; Souza, Alejandro J.

    2012-07-01

    Sea level comprises a mean level, tidal elevation and a residual elevation. Knowledge of what causes maximum water levels is often key in coastal management. However, different methods to extract deviations in water level (residuals) from modelled and observed elevation can give different results. The Dee Estuary, northwest England is a macrotidal estuary that undergoes periodic stratification. It is used here to demonstrate methods to extract the residual water level in response to the following interactive processes: tidal, river-induced stratification and flow, meteorology and waves. Using modelling techniques, the interaction and contribution of different physical processes are investigated. Classical harmonic tidal analysis, model simulations and filtering techniques have been used to "de-tide" the total elevation for short-term (approximately month long) records. Each technique gives a different result highlighting the need to select the correct method for a required study. Analysis of the residual components demonstrates that all processes inducing residuals interact with the tide generating a semi-diurnal residual component. It is suggested that modelling methods enable the full effect of tidal interaction to remain in the residual, whilst harmonic tidal analysis (partly) modify and filtering methods (fully) remove this component of the residual. The analysis methods presented and their influences on the resultant residual are applicable to other study sites. However, when applied specifically to the mouth of the Dee Estuary, the external surge is found to be the main contributor to the total residual, whilst local wind and stratification effects are of secondary importance.

  5. Heartbeat Stars: A Class Of Tidally Excited Eccentric Binaries

    Science.gov (United States)

    Barclay, Thomas; Thompson, S. E.; Mullally, F.; Everett, M.; Howell, S. B.; Still, M.; Christiansen, J. L.; Rowe, J.; Kurtz, D. W.; Hambleton, K.

    2012-01-01

    We have discovered a class of eccentric binary systems undergoing dynamic tidal distortions and tidally induced pulsations in the Kepler data. Each has a uniquely shaped light curve that is characterized by periodic brightening or variability at time scales of 4-20 days which is frequently accompanied by shorter period oscillations. We can explain the dominant features of the entire class with changing tidal forces that occur in close, eccentric binary systems. In this case the large variety of light curve shapes arises from viewing systems at different angles. A hypothesis that is confirmed with radial velocity measurements that show an eccentric orbit. Prior to the discovery of these 17 new systems, KOI-54 was the only system with direct detection of these dynamic tides and tidally induced oscillations. While significant work remains to include all the physics required to accurately model these systems and begin to understand how tidal effects influence the system, in this presentation we present preliminary fits to the light curves and describe the properties of this class of stars as a whole.

  6. Multiscale analyses of solar-induced florescence and gross primary production

    Science.gov (United States)

    Wood, Jeffrey D.; Griffis, Timothy J.; Baker, John M.; Frankenberg, Christian; Verma, Manish; Yuen, Karen

    2017-01-01

    Solar-induced fluorescence (SIF) has shown great promise for probing spatiotemporal variations in terrestrial gross primary production (GPP), the largest component flux of the global carbon cycle. However, scale mismatches between SIF and ground-based GPP have posed challenges toward fully exploiting these data. We used SIF obtained at high spatial sampling rates and resolution by NASA's Orbiting Carbon Observatory-2 satellite to elucidate GPP-SIF relationships across space and time in the U.S. Corn Belt. Strong linear scaling functions (R2 ≥ 0.79) that were consistent across instantaneous to monthly time scales were obtained for corn ecosystems and for a heterogeneous landscape based on tall tower observations. Although the slope of the corn function was 56% higher than for the landscape, SIF was similar for corn (C4) and soybean (C3). Taken together, there is strong observational evidence showing robust linear GPP-SIF scaling that is sensitive to plant physiology but insensitive to the spatial or temporal scale.

  7. Fungal-Induced Deterioration of Mural Paintings: In Situ and Mock-Model Microscopy Analyses.

    Science.gov (United States)

    Unković, Nikola; Grbić, Milica Ljaljević; Stupar, Miloš; Savković, Željko; Jelikić, Aleksa; Stanojević, Dragan; Vukojević, Jelena

    2016-04-01

    Fungal deterioration of frescoes was studied in situ on a selected Serbian church, and on a laboratory model, utilizing standard and newly implemented microscopy techniques. Scanning electron microscopy (SEM) with energy-dispersive X-ray confirmed the limestone components of the plaster. Pigments used were identified as carbon black, green earth, iron oxide, ocher, and an ocher/cinnabar mixture. In situ microscopy, applied via a portable microscope ShuttlePix P-400R, proved very useful for detection of invisible micro-impairments and hidden, symptomless, microbial growth. SEM and optical microscopy established that observed deterioration symptoms, predominantly discoloration and pulverization of painted layers, were due to bacterial filaments and fungal hyphal penetration, and formation of a wide range of fungal structures (i.e., melanized hyphae, chlamydospores, microcolonial clusters, Cladosporium-like conidia, and Chaetomium perithecia and ascospores). The all year-round monitoring of spontaneous and induced fungal colonization of a "mock painting" in controlled laboratory conditions confirmed the decisive role of humidity level (70.18±6.91% RH) in efficient colonization of painted surfaces, as well as demonstrated increased bioreceptivity of painted surfaces to fungal colonization when plant-based adhesives (ilinocopie, murdent), compared with organic adhesives of animal origin (bone glue, egg white), are used for pigment sizing.

  8. Methods for the Analyses of Inhibitor-Induced Aberrant Multimerization of HIV-1 Integrase

    Science.gov (United States)

    Kessl, Jacques J.; Sharma, Amit; Kvaratskhelia, Mamuka

    2016-01-01

    HIV-1 integrase (IN) is an important therapeutic target as its function is essential for the viral lifecycle. The discovery of multifunctional allosteric IN inhibitors or ALLINIs, which potently impair viral replication by promoting aberrant, higher order IN multimerization as well as inhibit IN interactions with its cellular cofactor, LEDGF/p75, has opened new venues to exploit IN multimerization as a therapeutic target. Furthermore, the recent discovery of multimerization selective IN inhibitors or MINIs, has provided new investigational probes to study the direct effects of aberrant IN multimerization in vitro and in infected cells. Here we describe three complementary methods designed to detect and quantify the effects of these new classes of inhibitors on IN multimerization. These methods include a homogenous time-resolved fluorescence-based assay which allows for measuring EC50 values for the inhibitor-induced aberrant IN multimerization, a dynamic light scattering-based assay which allows for monitoring the formation and sizes of oligomeric IN particles in a time-dependent manner, and a chemical cross-linking-based assay of interacting IN subunits which allows for the determination of IN oligomers in viral particles. PMID:26714710

  9. MACROSCOPIC ANALYSES OF THE EFFECTS OF HYALURONATES AND CORTICOSTEROIDS ON INDUCED OSTEOARTHRITIS IN RABBITS’ KNEES

    Science.gov (United States)

    Albano, Mauro Batista; Vidigal, Leandro; de Oliveira, Marcello Zaia; Namba, Mario Massatomo; da Silva, João Luiz Vieira; de Assis Pereira Filho, Francisco; Barbosa, Marcio Alves; da Silva, Elias Marcelo Batista

    2015-01-01

    Objective: To evaluate the effects of intra-articular injections of corticosteroids, native hyaluronic acid and branched-chain hyaluronic acid in experimentally-induced osteoarthrosis. Methods: 44 rabbits underwent anterior cruciate ligament resection and were then divided into four groups of eleven. Group 1: one intra-articular injection of saline solution per week, for three weeks; Group 2: three injections (one per week) of native hyaluronic acid; Group 3: three injections (one per week) of branched-chain hyaluronic acid; Group 4: two injections of betamethasone with an interval of three weeks. The cartilage of the tibial plateaus was evaluated macroscopically twelve weeks after surgery. Changes to the joint surface were graded as follows: Grade 0: smooth joint surface without relief changes; Grade 1: rough surface without any depressions; Grade 2: similar to grade 1, but with depressions on the joint surface; and Grade 3: subchondral bone exposure. The statistical analysis consisted of the use of Student's t test, chi-square test and analysis of variance (ANOVA). The significance level used was 5%. Results: A statistical difference was found between the control group and the three study groups 2, 3, 4 in relation to the development and severity of arthrosis. However, there was no difference between the groups regarding the drugs studied. Conclusion: A similar degree of attenuation of the osteoarthrosis process in the rabbits’ knees was found with the use of intra-articular injections of low-molecular-weight and high-molecular-weight glycosaminoglycans, and the corticosteroid betamethasone, compared with placebo. PMID:27022552

  10. Harnessing Tidal Energy Using Vertical Axis Tidal Turbine

    Directory of Open Access Journals (Sweden)

    Syed Shah Khalid

    2013-01-01

    Full Text Available An overview of the current design practices in the field of Renewable Energy (RE is presented; also paper delineates the background to the development of unique and novel techniques for power generation using the kinetic energy of tidal streams and other marine currents. Also this study focuses only on vertical axis tidal turbine. Tidal stream devices have been developed as an alternative method of extracting the energy from the tides. This form of tidal power technology poses less threat to the environment and does not face the same limiting factors associated with tidal barrage schemes, therefore making it a more feasible method of electricity production. Large companies are taking interest in this new source of power. There is a rush to research and work with this new energy source. Marine scientists are looking into how much these will affect the environment, while engineers are developing turbines that are harmless for the environment. In addition, the progression of technological advancements tracing several decades of R & D efforts on vertical axis turbines is highlighted.

  11. Tidal disruption event demographics

    Science.gov (United States)

    Kochanek, C. S.

    2016-09-01

    We survey the properties of stars destroyed in tidal disruption events (TDEs) as a function of black hole (BH) mass, stellar mass and evolutionary state, star formation history and redshift. For M_{BH} ≲ 10^7 M_{⊙}, the typical TDE is due to a M* ˜ 0.3 M⊙ M-dwarf, although the mass function is relatively flat for M_{ast } ≲ M_{⊙}. The contribution from older main-sequence stars and sub-giants is small but not negligible. From MBH ≃ 107.5-108.5 M⊙, the balance rapidly shifts to higher mass stars and a larger contribution from evolved stars, and is ultimately dominated by evolved stars at higher BH masses. The star formation history has little effect until the rates are dominated by evolved stars. TDE rates should decline very rapidly towards higher redshifts. The volumetric rate of TDEs is very high because the BH mass function diverges for low masses. However, any emission mechanism which is largely Eddington-limited for low BH masses suppresses this divergence in any observed sample and leads to TDE samples dominated by MBH ≃ 106.0-107.5 M⊙ BHs with roughly Eddington peak accretion rates. The typical fall-back time is relatively long, with 16 per cent having tfb plausible if tfb has any relation to the transient rise time. For almost any BH mass function, systematic searches for fainter, faster time-scale TDEs in smaller galaxies, and longer time-scale TDEs in more massive galaxies are likely to be rewarded.

  12. On luminescence bleaching of tidal channel sediments

    DEFF Research Database (Denmark)

    Fruergaard, Mikkel; Pejrup, Morten; Murray, Andrew S.

    2015-01-01

    We investigate the processes responsible for bleaching of the quartz OSL signal from tidal channel sediment. Tidal dynamics are expected to play an important role for complete bleaching of tidal sediments. However, no studies have examined the amount of reworking occurring in tidal channels...... and on tidal flats due to the mixing caused by currents and waves. We apply bed level data to evaluate the amount of vertical sediment reworking in modern tidal channels and at a tidal flat. Cycles of deposition and erosion are measured with a bed level sensor, and the results show that gross sedimentation...... on the quantitative measures of sediment reworking, we suggest that repeated depositional and erosional cycles allow for complete bleaching of the tidal flat sediment, and we infer that quartz OSL dating can provide accurate ages for shallow tidal channel fill....

  13. Genetic and molecular analyses of UV radiation-induced mutations in the fem-3 gene of Caenorhabditis elegans

    Energy Technology Data Exchange (ETDEWEB)

    Hartman, P.S.; De Wilde, D.; Dwarakanath, V.N. [Texas Christian Univ., Fort Worth, TX (United States). Dept. of Biology

    1995-06-01

    The utility of a new target gene (fem-3) is described for investigating the molecular nature of mutagenesis in the nematode Caenorhabditis elegans. As a principal attribute, this system allows for the selection, maintenance and molecular analysis of any type of mutation that disrupts the gene, including deletions. In this study, 86 mutant strains were isolated, of which 79 proved to have mutations in fem-3. Twenty of these originally tested as homozygous inviable. Homozygous inviability was expected, as Stewart and coworkers had previously observed that, unlike in other organisms, most UV radiation-induced mutations in C. elegans are chromosomal rearrangements of deficiencies (Mutat. Res 249, 37-54, 1991). However, additional data, including Southern blot analyses on 49 of the strains, indicated that most of the UV radiation-induced fem-3 mutations were not deficiencies, as originally inferred from their homozygous inviability. Instead, the lethals were most likely ``coincident mutations`` in linked, essential genes that were concomitantly induced. As such, they were lost owing to genetic recombination during stock maintenance. As in mammalian cells, yeast and bacteria, the frequency of coincident mutations was much higher than would be predicted by chance. (Author).

  14. Comparative analyses of light-induced anthocyanin accumulation and gene expression between the ray florets and leaves in chrysanthemum.

    Science.gov (United States)

    Hong, Yan; Yang, Li-Wen; Li, Meng-Ling; Dai, Si-Lan

    2016-06-01

    Light is one of the key environmental factors that affect anthocyanin biosynthesis. However, the underlying molecular mechanism remains unclear, and many problems regarding phenotypic change and corresponding gene regulation have not been solved. In the present study, comparative analyses of light-induced anthocyanin accumulation and gene expression between the ray florets and leaves were performed in Chrysanthemum × morifolium 'Purple Reagan'. After contrasting the variations in the flower color phenotype and relative pigment content, as well as expression patterns of structural and regulator genes responsible for anthocyanin biosynthesis and photoreceptor between different plant organs under light and dark conditions, we concluded that (1) both the capitulum and foliage are key organs responding to light for chrysanthemum coloration; (2) compared with flavones, shading makes a greater decrease on the anthocyanins accumulation; (3) most of the structural and regulatory genes in the light-induced anthocyanin pathway specifically express in the ray florets; and (4) CmCHS, CmF3H, CmF3'H, CmANS, CmDFR, Cm3GT, CmMYB5-1, CmMYB6, CmMYB7-1, CmbHLH24, CmCOP1 and CmHY5 are key genes for light-induced anthocyanin biosynthesis in chrysanthemum ray florets, while on the transcriptional level, the expressions of CmPHYA, CmPHYB, CmCRY1a, CmCRY1b and CmCRY2 are insignificantly changed. Moreover, the inferred comprehensive effect of multiple signals on the accumulation of anthocyanins and transmission channel of light signal that exist between the leaves and ray florets were further discussed. These results further our understanding of the relationship between the gene expression and light-induced anthocyanin biosynthesis, and lay foundations for the promotion of the molecular breeding of novel flower colors in chrysanthemums.

  15. Tidal Models In A New Era of Satellite Gravimetry

    Science.gov (United States)

    Ray, Richard D.; Rowlings, David D.; Edbert, G. D.; Chao, Benjamin F. (Technical Monitor)

    2002-01-01

    The high precision gravity measurements to be made by recently launched (and recently approved) satellites place new demands on models of Earth, atmospheric, and oceanic tides. The latter is the most problematic. The ocean tides induce variations in the Earth's geoid by amounts that far exceed the new satellite sensitivities, and tidal models must be used to correct for this. Two methods are used here to determine the standard errors in current ocean tide models. At long wavelengths these errors exceed the sensitivity of the GRACE mission. Tidal errors will not prevent the new satellite missions from improving our knowledge of the geopotential by orders of magnitude, but the errors may well contaminate GRACE estimates of temporal variations in gravity. Solar tides are especially problematic because of their long alias periods. The satellite data may be used to improve tidal models once a sufficiently long time series is obtained. Improvements in the long-wavelength components of lunar tides are especially promising.

  16. Observational Evidence for Tidal Interaction in Close Binary Systems

    CERN Document Server

    Mazeh, Tsevi

    2008-01-01

    This paper reviews the rich corpus of observational evidence for tidal effects in short-period binaries. We review the evidence for ellipsoidal variability and for the observational manifestation of apsidal motion in eclipsing binaries. Among the long-term effects, circularization was studied the most, and a transition period between circular and eccentric orbits has been derived for eight coeval samples of binaries. As binaries are supposed to reach synchronization before circularization, one can expect finding eccentric binaries in pseudo-synchronization state, the evidence for which is reviewed. The paper reviews the Rossiter-McLaughlin effect and its potential to study spin-orbit alignment. We discuss the tidal interaction in close binaries that are orbited by a third distant companion, and review the effect of pumping the binary eccentricity by the third star. We then discuss the idea that the tidal interaction induced by the eccentricity modulation can shrink the binary separation. The paper discusses t...

  17. Tidal disruption of inviscid protoplanets

    Science.gov (United States)

    Boss, Alan P.; Cameron, A. G. W.; Benz, W.

    1991-01-01

    Roche showed that equilibrium is impossible for a small fluid body synchronously orbiting a primary within a critical radius now termed the Roche limit. Tidal disruption of orbitally unbound bodies is a potentially important process for planetary formation through collisional accumulation, because the area of the Roche limit is considerably larger then the physical cross section of a protoplanet. Several previous studies were made of dynamical tidal disruption and different models of disruption were proposed. Because of the limitation of these analytical models, we have used a smoothed particle hydrodynamics (SPH) code to model the tidal disruption process. The code is basically the same as the one used to model giant impacts; we simply choose impact parameters large enough to avoid collisions. The primary and secondary both have iron cores and silicate mantles, and are initially isothermal at a molten temperature. The conclusions based on the analytical and numerical models are summarized.

  18. Sediment Dynamics in Shallow Tidal Landscapes: The Role of Wind Waves and Tidal Currents

    Science.gov (United States)

    Carniello, L.; D'Alpaos, A.

    2014-12-01

    A precise description of sediment dynamics (resuspension and re-distribution of sediments) is crucial when investigating the long term evolution of the different morphological entities characterizing tidal landscapes. It has been demonstrated that wind waves are the main responsible for sediment resuspension in shallow micro-tidal lagoons where tidal currents, which produce shear stresses large enough to carry sediments into suspension only within the main channels, are mainly responsible for sediment redistribution. A mathematical model has been developed to describe sediment entrainment, transport and deposition due to the combined effect of tidal currents and wind waves in shallow lagoons considering both cohesive and non-cohesive sediments. The model was calibrated and tested using both in situ point observations and turbidity maps obtained analyzing satellite images. Once calibrated the model can integrate the high temporal resolution of point observations with the high spatial resolution of remote sensing, overcoming the intrinsic limitation of these two types of observations. The model was applied to the specific test case of the Venice lagoon simulating an entire year (2005) which was shown to be a "representative" year for wind and tide characteristics. The time evolution of the computed total bottom shear stresses (BSS) and suspended sediment concentration (SSC) was analyzed on the basis of a "Peaks Over Threshold" method once a critical value for shear stress and turbidity were chosen. The analyses of the numerical results enabled us to demonstrate that resuspension events can be modeled as marked Poisson processes: interarrival time, intensity of peak excesses and duration being exponentially distributed random variable. The probability distributions of the interarrival time of overthreshold exceedances in both BSS and SSC as well as their intensity and duration can be used in long-term morphodynamic studies to generate synthetic series statistically

  19. The distribution and tapping tidal energy

    Directory of Open Access Journals (Sweden)

    Zygmunt Kowalik

    2004-09-01

    Full Text Available Tidal power along tidal shores has been used for centuries to run small tidal mills. Generating electricity by tapping tidal power proved to be very successful only in the last century through the tidal power plant constructed in 1967 in La Rance, France. This used a large barrier to generate the sea level head necessary for driving turbines. Construction of such plants evolved very slowly because of prohibitive costs and concerns about the environmental impact. Developments in the construction of small, efficient and inexpensive underwater turbines admit the possibility of small scale operations that will use local tidal currents to bring electricity to remote locations. Since the generation of such electricity is concerned with the tidal energy in local water bodies, it is important to understand the site-specific energy balance, i.e., the energy flowing in through open boundaries, and the energy generated and dissipated within the local domain. The question is how to tap the tidal energy while keeping possible changes in the present tidal regimes to a minimum. The older approach of constructing barrages may still be quite useful in some locations. The basics of such tidal power plants constructed in a small bay are analyzed in order to understand the principal parameter for tidal plant evaluation, i.e., the power produced.     The new approach is to place turbines - devices similar to windmills - in the pathway of tidal currents. Theoretically, the amount of power available by such turbines for electricity generation is proportional to the water density and velocity cubed of the tidal flow. The naturally dissipated tidal power due to bottom friction forces is also proportional to the cube of the velocity. Because of this similarity, the exploitation of tidal energy can be directed to reinvesting the naturally dissipated power into tidal power for the generation of electricity. This approach to tidal power exploitation is better tuned

  20. Relativistic theory of tidal Love numbers

    OpenAIRE

    Binnington, Taylor; Poisson, Eric

    2009-01-01

    In Newtonian gravitational theory, a tidal Love number relates the mass multipole moment created by tidal forces on a spherical body to the applied tidal field. The Love number is dimensionless, and it encodes information about the body's internal structure. We present a relativistic theory of Love numbers, which applies to compact bodies with strong internal gravities; the theory extends and completes a recent work by Flanagan and Hinderer, which revealed that the tidal Love number of a neut...

  1. Tidal Level Response to Sea-Level Rise in the Yangtze Estuary

    Institute of Scientific and Technical Information of China (English)

    GONG Zheng; ZHANG Chang-kuan; WAN Li-ming; ZUO Jun-cheng

    2012-01-01

    The rise of tidal level in tidal reaches induced by sea-level rise has a large impact on flood control and water supply for the regions around the estuary.This paper focuses on the variations of tidal level response along the tidal reaches in the Yangtze Estuary,as well as the impacts of upstream discharge on tidal level response,due to the sea-level rise of the East China Sea.Based on the Topex/Poseidon altimeter data obtained during the period 1993~2005,a stochastic dynamic analysis was performed and a forecast model was run to predict the sea-level rise of the East China Sea.Two-dimensional hydrodynamic numerical models downscaling from the East China Sea to estuarine areas were implemented to analyze the rise of tidal level along the tidal reaches.In response to the sea-level rise,the tidal wave characteristics change slightly in nearshore areas outside the estuaries,involving the tidal range and the duration of flood and ebb tide.The results show that the rise of tidal level in the tidal reaches due to the sea-level rise has upstream decreasing trends.The step between the stations of Zhangjiagang and Shiyiwei divides the tidal reaches into two parts,in which the tidal level response declines slightly.The rise of tidal level is 1~2.5 mm/a in the upper part,and 4~6 mm/a in the lower part.The stations of Jiangyin and Yanglin,as an example of the upper part and the lower part respectively,are extracted to analyze the impacts of upstream discharge on tidal level response to the sea-level rise.The relation between the rise of tidal level and the upstream discharge can be fitted well with a quadratic function in the upper part.However,the relation is too complicated to be fitted in the lower part because of the tide dominance.For comparison purposes,hourly tidal level observations at the stations of Xuliujing and Yanglin during the period 1993~2009 are adopted.In order to uniform the influence of upstream discharge on tidal level for a certain day each year

  2. Heartbeat Stars and the Ringing of Tidal Pulsations

    Directory of Open Access Journals (Sweden)

    Hambleton Kelly

    2015-01-01

    Full Text Available With the advent of high precision photometry from satellites such as Kepler and CoRoT, a whole new layer of interesting and astounding astronomical objects has been revealed: heartbeat stars are an example of such objects. Heartbeat stars are eccentric ellipsoidal variables that undergo strong tidal interactions when the stars are almost in contact at the time of closest approach. These interactions deform of the stars and cause a notable light curve variation in the form of a tidal pulse. A subset of these objects (~20% show prominent tidally induced pulsations: pulsations forced by the binary orbit. We now have a fully functional code that models binary star features (using PHOEBE and stellar pulsations simultaneously, enabling a complete and accurate heartbeat star model to be determined. In this paper we show the results of our new code, which uses emcee, a variant of mcmc, to generate a full set of stellar parameters. We further highlight the interesting features of KIC 8164262, including its tidally induced pulsations and resonantly locked pulsations.

  3. Structural and tidal models of Titan and inferences on cryovolcanism

    Science.gov (United States)

    Sohl, F.; Solomonidou, A.; Wagner, F. W.; Coustenis, A.; Hussmann, H.; Schulze-Makuch, D.

    2014-05-01

    Titan, Saturn's largest satellite, is subject to solid body tides exerted by Saturn on the timescale of its orbital period. The tide-induced internal redistribution of mass results in tidal stress variations, which could play a major role for Titan's geologic surface record. We construct models of Titan's interior that are consistent with the satellite's mean density, polar moment-of-inertia factor, obliquity, and tidal potential Love number k2 as derived from Cassini observations of Titan's low-degree gravity field and rotational state. In the presence of a global liquid reservoir, the tidal gravity field is found to be consistent with a subsurface water-ammonia ocean more than 180 km thick and overlain by an outer ice shell of less than 110 km thickness. The model calculations suggest comparatively low ocean ammonia contents of less than 5 wt % and ocean temperatures in excess of 255 K, i.e., higher than previously thought, thereby substantially increasing Titan's potential for habitable locations. The calculated diurnal tidal stresses at Titan's surface amount to 20 kPa, almost comparable to those expected at Enceladus and Europa. Tidal shear stresses are concentrated in the polar areas, while tensile stresses predominate in the near-equatorial, midlatitude areas of the sub- and anti-Saturnian hemispheres. The characteristic pattern of maximum diurnal tidal stresses is largely compliant with the distribution of active regions such as cryovolcanic candidate areas. The latter could be important for Titan's habitability since those may provide possible pathways for liquid water-ammonia outbursts on the surface and the release of methane in the satellite's atmosphere.

  4. General relativistic tidal heating for Moller pseudotensor

    CERN Document Server

    So, Lau Loi

    2015-01-01

    Thorne elucidated that the relativistic tidal heating is the same as the Newtonian theory. Moreover, Thorne also claimed that the tidal heating is independent of how one localizes gravitational energy and is unambiguously given by a certain formula. Purdue and Favata calculated the tidal heating for different classical pseudotensors including Moller and obtained the results all matched with the Newtonian perspective. After re-examined this Moller pseudotensor, we find that there does not exist any tidal heating value. Thus we claim that the relativistic tidal heating is pseudotensor independent under the condition that if the peusdotensor is a Freud typed superpotential.

  5. Observed wintertime tidal and subtidal currents over the continental shelf in the northern South China Sea

    Science.gov (United States)

    Li, Ruixiang; Chen, Changsheng; Xia, Huayong; Beardsley, Robert C.; Shi, Maochong; Lai, Zhigang; Lin, Huichan; Feng, Yanqing; Liu, Changjian; Xu, Qichun; Ding, Yang; Zhang, Yu

    2014-08-01

    Synthesis analyses were performed to examine characteristics of tidal and subtidal currents at eight mooring sites deployed over the northern South China Sea (NSCS) continental shelf in the 2006-2007 and 2009-2010 winters. Rotary spectra and harmonic analysis results showed that observed tidal currents in the NSCS were dominated by baroclinic diurnal tides with phases varying both vertically and horizontally. This feature was supported by the CC-FVCOM results, which demonstrated that the diurnal tidal flow over this shelf was characterized by baroclinic Kelvin waves with vertical phase differences varying in different flow zones. The northeasterly wind-induced southwestward flow prevailed over the NSCS shelf during winter, with episodic appearances of mesoscale eddies and a bottom-intensified buoyancy-driven slope water intrusion. The moored current records captured a warm-core anticyclonic eddy, which originated from the southwestern coast of Taiwan and propagated southwestward along the slope consistent with a combination of β-plane and topographic Rossby waves. The eddy was surface-intensified with a swirl speed of >50 cm/s and a vertical scale of ˜400 m. In absence of eddies and onshore deep slope water intrusion, the observed southwestward flow was highly coherent with the northeasterly wind stress. Observations did not support the existence of the permanent wintertime South China Sea Warm Current (SCSWC). The definition of SCSWC, which was based mainly on thermal wind calculations with assumed level of no motion at the bottom, needs to be interpreted with caution since the observed circulation over the NSCS shelf in winter included both barotropic and baroclinic components.

  6. Marsh Pool and Tidal Creek Morphodynamics: Dynamic Equilibrium of New England Saltmarshes?

    Science.gov (United States)

    Wilson, C.; FitzGerald, D. M.; Hughes, Z. J.

    2012-12-01

    Under natural conditions, high saltmarsh platforms in New England exhibit poor drainage, creating waterlogged pannes (where short-form Spartina alterniflora dominates) and stagnant pools that experience tidal exchange only during spring tides and storm-induced flooding events. It is well accepted that a legacy of ditching practices (either for agriculture or mosquito control purposes) provide "overdrainage" of saltmarshes (after Redfield, 1972) and a shift in biogeochemical conditions: lowering of groundwater tables, aeration of soil, and decrease in preserved belowground biomass. Analysis of historical imagery in the Plum Island Estuary of Massachusetts reveals closure and decrease in length of anthropogenic ditches in recent decades is closely linked to marsh pool evolution. Field analyses including stratigraphic transects and elevation surveys suggest these marshes are reverting to natural drainage conditions. Further, an important dynamic interaction exists between saltmarsh pools and natural tidal creeks: creeks incise into pool areas, causing drainage of the pools, and formation of an unvegetated mudflat which can be rapidly recolonized by halophytic Spartina alterniflora vegetation. It was determined that pool and creek dynamics are cyclic in nature. The marsh platform is in dynamic equilibrium with respect to elevation and sea-level whereby marsh elevation may be lost (due to degradation of organic matter and formation of a pool) however may be regained (by creek incision into pools, restoration of tidal exchange, and rapid vertical accretion with Spartina alterniflora recolonization. Since vertical accretion in saltmarshes is a function of both organic and inorganic contributions to the marsh subsurface, it is hypothesized that cannibalization of existing muds is supplying inorganic material in this sediment starved system.

  7. Tidal flow separation at protruding beach nourishments

    Science.gov (United States)

    Radermacher, Max; de Schipper, Matthieu A.; Swinkels, Cilia; MacMahan, Jamie H.; Reniers, Ad J. H. M.

    2017-01-01

    In recent years, the application of large-scale beach nourishments has been discussed, with the Sand Motor in the Netherlands as the first real-world example. Such protruding beach nourishments have an impact on tidal currents, potentially leading to tidal flow separation and the generation of tidal eddies of length scales larger than the nourishment itself. The present study examines the characteristics of the tidal flow field around protruding beach nourishments under varying nourishment geometry and tidal conditions, based on extensive field observations and numerical flow simulations. Observations of the flow field around the Sand Motor, obtained with a ship-mounted current profiler and a set of fixed current profilers, show that a tidal eddy develops along the northern edge of the mega-nourishment every flood period. The eddy is generated around peak tidal flow and gradually gains size and strength, growing much larger than the cross-shore dimension of the coastline perturbation. Based on a 3 week measurement period, it is shown that the intensity of the eddy modulates with the spring-neap tidal cycle. Depth-averaged tidal currents around coastline perturbations are simulated and compared to the field observations. The occurrence and behavior of tidal eddies is derived for a large set of simulations with varying nourishment size and shape. Results show that several different types of behavior exist, characterized by different combinations of the nourishment aspect ratio, the size of the nourishment relative to the tidal excursion length, and the influence of bed friction.

  8. Maine Tidal Power Initiative: Environmental Impact Protocols For Tidal Power

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Michael Leroy [Univ. of Maine, Orono, ME; Zydlewski, Gayle Barbin [Univ. of Maine, Orono, ME; Xue, Huijie [Univ. of Maine, Orono, ME; Johnson, Teresa R. [Univ. of Maine, Orono, ME

    2014-02-02

    The Maine Tidal Power Initiative (MTPI), an interdisciplinary group of engineers, biologists, oceanographers, and social scientists, has been conducting research to evaluate tidal energy resources and better understand the potential effects and impacts of marine hydro-kinetic (MHK) development on the environment and local community. Project efforts include: 1) resource assessment, 2) development of initial device design parameters using scale model tests, 3) baseline environmental studies and monitoring, and 4) human and community responses. This work included in-situ measurement of the environmental and social response to the pre-commercial Turbine Generator Unit (TGU®) developed by Ocean Renewable Power Company (ORPC) as well as considering the path forward for smaller community scale projects.

  9. Survey of Morphological Changes on Tidal Flats in Estuaries

    Science.gov (United States)

    Albers, Thorsten; von Lieberman, Nicole

    2010-05-01

    Tidal flat areas in estuaries are affected by strong morphodynamics. Changes of sedimentation and erosion occur on very different time and spatial scales. These changes challenge the responsible authorities due to the high importance of sufficient navigation channel depths and the ecological importance of those unique zones. The Hamburg University of Technology in cooperation with the Hamburg Port Authority runs broad field measurements on different tidal flat areas in the Elbe estuary. The results provide a fundamental data set, which improves the knowledge about morphodynamic processes and verifies mathematical descriptions. The field measurements focus on two investigation areas: One area is located in the mouth of the estuary and represents a marine tidal flat. The other one is located near the city of Hamburg and typifies a limnic tidal flat area. For more than 3 years water levels, waves, current parameters and suspended sediment concentrations are being recorded continuously and in a high resolution at different positions. Altogether, three measuring positions are operated at any time. To observe the consequences of the morphodynamic processes, the bathymetry of the investigation areas is determined with a multi-beam echo sounder (MBES) in frequent intervals. The main goal of the research project is to improve the knowledge about morphodynamic processes on tidal flats. Derived from the field data certain patterns of erosion, sediment transport and sedimentation could be observed depending on tidal currents, waves and large scale weather conditions. Seasonal effects are analysed as well as the influence of extreme events. A comparison of the processes observed on marine and limnic areas is done, whereas the latter additionally is affected by upstream water discharge. For example, on the marine tidal flats the sediment transport capacity was analysed: Extreme events cause a short peak, which does not result in significant bathymetric changes. Larger

  10. Effects of Magnetic Braking and Tidal Friction on Hot Jupiters

    CERN Document Server

    Barker, A J

    2009-01-01

    Tidal friction is thought to be important in determining the long-term spin-orbit evolution of short-period extrasolar planetary systems. Using a simple model of the orbit-averaged effects of tidal friction Eggleton, Kiseleva & Hut (1998), we analyse the effects of the inclusion of stellar magnetic braking on the evolution of such systems. A phase-plane analysis of a simplified system of equations, including only the stellar tide together with a model of the braking torque proposed by Verbunt & Zwaan (1981), is presented. The inclusion of stellar magnetic braking is found to be extremely important in determining the secular evolution of such systems, and its neglect results in a very different orbital history. We then show the results of numerical integrations of the full tidal evolution equations, using the misaligned spin and orbit of the XO-3 system as an example, to study the accuracy of simple timescale estimates of tidal evolution. We find that it is essential to consider coupled evolution of th...

  11. 3-D modelling the electric field due to ocean tidal flow and comparison with observations

    DEFF Research Database (Denmark)

    Kuvshinov, A.; Junge, A.; Utada, H.

    2006-01-01

    of the global distribution of the electric signal due to tidal ocean flow. We simulate the electric signals for two tidal constituents - lunar semidiurnal (M2) and diurnal (O1) tides. We assume a realistic Earth's conductivity model with a surface thin shell and 1-D mantle underneath. Simulations demonstrate......The tidal motion of the ocean water through the ambient magnetic field, generates secondary electric field. This motionally induced electric field can be detected in the sea or inland and has a potential for electrical soundings of the Earth. A first goal of the paper is to gain an understanding...

  12. Trans World Tidal Gravity Profile.

    Science.gov (United States)

    1984-12-31

    America Curitiba (BraziZ) This station, situated at the Universidade Federal do Parana, in the Instituto de Ciencias Geod6sicas under Professor C...SUL COMPOSANTE VEPTICALE ERESIL 29 40 17S 53 49 22W H 700M P 2M 0 330KM DEPOTS SEDIMENTAIRES SUk BASALTE DEPT* DE INGENIERIA RURAL-UNIV. FED. DE SANTA...PRECAMBRIENIGNEISS * UNIVERSIDADE FEDERAL DO RIO GRANDE DO NORTE - DEPARTAMENTO DE FISICA TRANS WORLD TIDAL GRAVITY PROFILES P. MELCHIOR CENTRO POLITECNICO

  13. Tidal Limits to Planetary Habitability

    CERN Document Server

    Barnes, Rory; Greenberg, Richard; Raymond, Sean N

    2009-01-01

    The habitable zones of main sequence stars have traditionally been defined as the range of orbits that intercept the appropriate amount of stellar flux to permit surface water on a planet. Terrestrial exoplanets discovered to orbit M stars in these zones, which are close-in due to decreased stellar luminosity, may also undergo significant tidal heating. Tidal heating may span a wide range for terrestrial exoplanets and may significantly affect conditions near the surface. For example, if heating rates on an exoplanet are near or greater than that on Io (where tides drive volcanism that resurface the planet at least every 1 Myr) and produce similar surface conditions, then the development of life seems unlikely. On the other hand, if the tidal heating rate is less than the minimum to initiate plate tectonics, then CO_2 may not be recycled through subduction, leading to a runaway greenhouse that sterilizes the planet. These two cases represent potential boundaries to habitability and are presented along with th...

  14. Chaotic Dispersal of Tidal Debris

    CERN Document Server

    Price-Whelan, Adrian M; Valluri, Monica; Pearson, Sarah; Kupper, Andreas H W; Hogg, David W

    2015-01-01

    Several long, dynamically cold stellar streams have been observed around the Milky Way Galaxy, presumably formed from the tidal disruption of globular clusters. In integrable potentials---where all orbits are dynamically regular---tidal debris phase-mixes close to the orbit of the progenitor system. However, cosmological simulations of structure formation suggest that the Milky Way's dark matter halo is expected not to be fully integrable; an appreciable fraction of orbits will be chaotic. This paper examines the influence of chaos on the phase-space morphology of cold tidal streams. We find very stark results: Streams in chaotic regions look very different from those in regular regions. We find that streams (simulated using test particle ensembles of nearby orbits) can be sensitive to chaos on a much shorter time-scale than any standard prediction (from the Lyapunov or frequency-diffusion times). For example, on a weakly chaotic orbit with a chaotic timescale predicted to be >1000 orbital periods (>1000 Gyr)...

  15. North American tidal power prospects

    Science.gov (United States)

    Wayne, W. W., Jr.

    1981-07-01

    Prospects for North American tidal power electrical generation are reviewed. Studies by the US Army Corps of Engineers of 90 possible generation schemes in Cobscook Bay, ME, indicated that maximum power generation rather than dependable capacity was the most economic method. Construction cost estimates for 15 MW bulb units in a single effect mode from basin to the sea are provided; five projects were considered ranging from 110-160 MW. Additional tidal power installations are examined for: Half-Moon Cove, ME (12 MW, 18 ft tide); Cook Inlet, AK, which is shown to pose severe environmental and engineering problems due to fish migration, earthquake hazards, and 300 ft deep silt deposits; and the Bay of Fundy, Canada. This last has a 17.8 MW plant under construction in a 29 ft maximum tide area. Other tidal projects of the Maritime Provinces are reviewed, and it is noted that previous economic evaluations based on an oil price of $16/barrel are in need of revision.

  16. Extensive structural change of the envelope protein of dengue virus induced by a tuned ionic strength: conformational and energetic analyses

    Science.gov (United States)

    Degrève, Léo; Fuzo, Carlos A.; Caliri, Antonio

    2012-12-01

    The Dengue has become a global public health threat, with over 100 million infections annually; to date there is no specific vaccine or any antiviral drug. The structures of the envelope (E) proteins of the four known serotype of the dengue virus (DENV) are already known, but there are insufficient molecular details of their structural behavior in solution in the distinct environmental conditions in which the DENVs are submitted, from the digestive tract of the mosquito up to its replication inside the host cell. Such detailed knowledge becomes important because of the multifunctional character of the E protein: it mediates the early events in cell entry, via receptor endocytosis and, as a class II protein, participates determinately in the process of membrane fusion. The proposed infection mechanism asserts that once in the endosome, at low pH, the E homodimers dissociate and insert into the endosomal lipid membrane, after an extensive conformational change, mainly on the relative arrangement of its three domains. In this work we employ all-atom explicit solvent Molecular Dynamics simulations to specify the thermodynamic conditions in that the E proteins are induced to experience extensive structural changes, such as during the process of reducing pH. We study the structural behavior of the E protein monomer at acid pH solution of distinct ionic strength. Extensive simulations are carried out with all the histidine residues in its full protonated form at four distinct ionic strengths. The results are analyzed in detail from structural and energetic perspectives, and the virtual protein movements are described by means of the principal component analyses. As the main result, we found that at acid pH and physiological ionic strength, the E protein suffers a major structural change; for lower or higher ionic strengths, the crystal structure is essentially maintained along of all extensive simulations. On the other hand, at basic pH, when all histidine residues are in

  17. A STUDY ON EQUILIBRIUM COASTAL PROFILES OF THE CLOSE TIDAL FLAT--A Case Study of Fengxian Tidal Flat

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The article analyses the temporal-spatial changes of profiles by EOF (Empirical Orthogonal Function) analy-sis and DTM analysis of GIS. These profiles, which are not affected by engineering, are chosen from the coast with succes-sive field monitoring data from 1990 to 1999. Temporal and spatial EOF indicates the obvious stability of coast profile param-eters in Fengxian tidal flat. In spatial scale, high tidal flats and deep-water terraces are in a balance state while upperclino with steep slopes are sensitive and the stability is easy to be destroyed. In temporal scale, the erosion and deposi-tion in this area are kept in balance in a whole. There are almost no change below -8 - -9.5m. At the same time, it isthe lower limit of tidal affection and the erosion and deposition process from it to high tidal flat keep in balance for manyyears. So the closure depth is appointed to from -8m to -9.5 m (Wusong datum mark).

  18. Star Formation in NGC4532/DDO 137'S Tidal Dwarf Galaxies and 500 KPC HI Stream

    Science.gov (United States)

    Higdon, Sarah

    Mergers and close-passages between gas rich galaxies can result in the formation of long HI/stellar streams. The tidally induced star formation and gas concentrations can result in the creation of tidal dwarf galaxies (TDGs). TDGs may contribute significantly to the dwarf galaxy population, by far the most common galaxy type in the current epoch. We have discovered one of the longest known tidal streams (500 kpc) in the NGC 4535/DDO 137 system. We propose 3 ksec FUV/NUV images centered on the stream and its five TDGs. We will readily detect faint/low mass star forming regions (~2E-17 erg s-1 cm-2 A-1) to 5-sigma. The GALEX observations are a unique opportunity to undertake a sensitive and comprehensive study of tidally induced star formation, dwarf galaxy formation and inter-galactic enrichment in this system.

  19. ARE TIDAL EFFECTS RESPONSIBLE FOR EXOPLANETARY SPIN–ORBIT ALIGNMENT?

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gongjie [Harvard-Smithsonian Center for Astrophysics, The Institute for Theory and Computation, 60 Garden Street, Cambridge, MA 02138 (United States); Winn, Joshua N., E-mail: gli@cfa.harvard.edu [Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    2016-02-10

    The obliquities of planet-hosting stars are clues about the formation of planetary systems. Previous observations led to the hypothesis that for close-in giant planets, spin–orbit alignment is enforced by tidal interactions. Here, we examine two problems with this hypothesis. First, Mazeh and coworkers recently used a new technique—based on the amplitude of starspot-induced photometric variability—to conclude that spin–orbit alignment is common even for relatively long-period planets, which would not be expected if tides were responsible. We re-examine the data and find a statistically significant correlation between photometric variability and planetary orbital period that is qualitatively consistent with tidal interactions. However it is still difficult to explain quantitatively, as it would require tides to be effective for periods as long as tens of days. Second, Rogers and Lin argued against a particular theory for tidal re-alignment by showing that initially retrograde systems would fail to be re-aligned, in contradiction with the observed prevalence of prograde systems. We investigate a simple model that overcomes this problem by taking into account the dissipation of inertial waves and the equilibrium tide, as well as magnetic braking. We identify a region of parameter space where re-alignment can be achieved, but it only works for close-in giant planets, and requires some fine tuning. Thus, while we find both problems to be more nuanced than they first appeared, the tidal model still has serious shortcomings.

  20. Stratification on the Skagit Bay Tidal Flats

    Science.gov (United States)

    2012-09-01

    al., 2009; Giddings et al., 2011) where the length of the salinity transition is similar to the tidal intrusion , tidal flats and the associated...tidal cycle as well as from the intrusion of incoming Puget Sound water into the residual river water. As in prior studies, the water becomes...effects of different orientations of the fresh- and saltwater sources 76 77 Appendix: Mixing Parameterization The mixing term M in the

  1. Tidal friction in close-in planets

    Science.gov (United States)

    Rodríguez, Adrián; Ferraz-Mello, Sylvio; Hussmann, Hauke

    2008-05-01

    We use Darwin's theory (Darwin, 1880) to derive the main results on the orbital and rotational evolution of a close-in companion (exoplanet or planetary satellite) due to tidal friction. The given results do not depend on any assumption linking the tidal lags to the frequencies of the corresponding tide harmonics (except that equal frequency harmonics are assumed to span equal lags). Emphasis is given to the study of the synchronization of the planetary rotation in the two possible final states for a non-zero eccentricity : (1) the super-synchronous stationary rotation resulting from the vanishing of the average tidal torque; (2) the capture into a 1:1 spin-orbit resonance (true synchronization), which is only possible if an additional torque exists acting in opposition to the tidal torque. Results are given under the assumption that this additional torque is produced by a non-tidal permanent equatorial asymmetry of the planet. The indirect tidal effects and some non-tidal effects due to that asymmetry are considered. For sake of comparison with other works, the results obtained when tidal lags are assumed proportional to the corresponding tidal wave frequencies are also given.

  2. Tracking Down the Causes of Recent Induced and Natural Intraplate Earthquakes with 3D Seismological Analyses in Northwest Germany

    Science.gov (United States)

    Uta, P.; Brandes, C.; Boennemann, C.; Plenefisch, T.; Winsemann, J.

    2015-12-01

    Northwest Germany is a typical low strain intraplate region with a low seismic activity. Nevertheless, 58 well documented earthquakes with magnitudes of 0.5 - 4.3 affected the area in the last 40 years. Most of the epicenters were located in the vicinity of active natural gas fields and some inside. Accordingly, the earthquakes were interpreted as a consequence of hydrocarbon recovery (e.g. Dahm et al. 2007, Bischoff et al. 2013) and classified as induced events in the bulletins of the Federal Institute for Geosciences and Natural Resources (BGR). The two major ones have magnitudes of 4.3 and 4.0. They are the strongest earthquakes ever recorded in Northern Germany. Consequently, these events raise the question whether the ongoing extraction itself can cause them or if other natural tectonic processes like glacial isostatic adjustment may considerably contribute to their initiation. Recent studies of Brandes et al. (2012) imply that lithospheric stress changes due to post glacial isostatic adjustment might be also a potential natural cause for earthquakes in Central Europe. In order to better analyse the earthquakes and to test this latter hypothesis we performed a relocalization of the events with the NonLinLoc (Lomax et al. 2000) program package and two differently scaled 3D P-wave velocity models. Depending on the station coverage for a distinct event, either a fine gridded local model (88 x 73 x 15 km, WEG-model, made available by the industry) or a coarse regional model (1600 x 1600 x 45 km, data from CRUST1.0, Laske et al. 2013) and for some cases a combination of both models was used for the relocalization. The results confirm the trend of the older routine analysis: The majority of the events are located at the margins of the natural gas fields, some of them are now located closer to them. Focal depths mostly vary between 3.5 km and 10 km. However, for some of the events, especially for the older events with relatively bad station coverage, the error bars

  3. Tidal Evolution of Asteroidal Binaries. Ruled by Viscosity. Ignorant of Rigidity.

    Science.gov (United States)

    Efroimsky, Michael

    2015-10-01

    This is a pilot paper serving as a launching pad for study of orbital and spin evolution of binary asteroids. The rate of tidal evolution of asteroidal binaries is defined by the dynamical Love numbers kl divided by quality factors Q. Common in the literature is the (oftentimes illegitimate) approximation of the dynamical Love numbers with their static counterparts. Since the static Love numbers are, approximately, proportional to the inverse rigidity, this renders a popular fallacy that the tidal evolution rate is determined by the product of the rigidity by the quality factor: {k}l/Q\\propto 1/(μ Q). In reality, the dynamical Love numbers depend on the tidal frequency and all rheological parameters of the tidally perturbed body (not just rigidity). We demonstrate that in asteroidal binaries the rigidity of their components plays virtually no role in tidal friction and tidal lagging, and thereby has almost no influence on the intensity of tidal interactions (tidal torques, tidal dissipation, tidally induced changes of the orbit). A key quantity that overwhelmingly determines the tidal evolution is a product of the effective viscosity η by the tidal frequency χ . The functional form of the torque’s dependence on this product depends on who wins in the competition between viscosity and self-gravitation. Hence a quantitative criterion, to distinguish between two regimes. For higher values of η χ , we get {k}l/Q\\propto 1/(η χ ), {while} for lower values we obtain {k}l/Q\\propto η χ . Our study rests on an assumption that asteroids can be treated as Maxwell bodies. Applicable to rigid rocks at low frequencies, this approximation is used here also for rubble piles, due to the lack of a better model. In the future, as we learn more about mechanics of granular mixtures in a weak gravity field, we may have to amend the tidal theory with other rheological parameters, ones that do not show up in the description of viscoelastic bodies. This line of study provides

  4. Protection against T1DM-Induced Bone Loss by Zinc Supplementation: Biomechanical, Histomorphometric, and Molecular Analyses in STZ-Induced Diabetic Rats.

    Directory of Open Access Journals (Sweden)

    Raul Hernandes Bortolin

    Full Text Available Several studies have established an association between diabetes and alterations in bone metabolism; however, the underlying mechanism is not well established. Although zinc is recognized as a potential preventive agent against diabetes-induced bone loss, there is no evidence demonstrating its effect in chronic diabetic conditions. This study evaluated the effects of zinc supplementation in a chronic (90 days type 1 diabetes-induced bone-loss model. Male Wistar rats were distributed in three groups: control, type 1 diabetes mellitus (T1DM, and T1DM plus zinc supplementation (T1DMS. Serum biochemical analysis; tibia histomorphometric, biomechanical, and collagen-content analyses; and femur mRNA expression were evaluated. Relative to T1DM, the zinc-supplemented group showed increased histomorphometric parameters such as TbWi and BAr and decreased TbSp, increased biomechanical parameters (maximum load, stiffness, ultimate strain, and Young's modulus, and increased type I collagen content. Interestingly, similar values for these parameters were observed between the T1DMS and control groups. These results demonstrate the protective effect of zinc on the maintenance of bone strength and flexibility. In addition, downregulation of OPG, COL1A, and MMP-9 genes was observed in T1DMS, and the anabolic effects of zinc were evidenced by increased OC expression and serum ALP activity, both related to osteoblastogenesis, demonstrating a positive effect on bone formation. In contrast, T1DM showed excessive bone loss, observed through reduced histomorphometric and biomechanical parameters, characterizing diabetes-associated bone loss. The bone loss was also observed through upregulation of OPG, COL1A, and MMP-9 genes. In conclusion, zinc showed a positive effect on the maintenance of bone architecture and biomechanical parameters. Indeed, OC upregulation and control of expression of OPG, COL1A, and MMP-9 mRNAs, even in chronic hyperglycemia, support an anabolic

  5. Protection against T1DM-Induced Bone Loss by Zinc Supplementation: Biomechanical, Histomorphometric, and Molecular Analyses in STZ-Induced Diabetic Rats.

    Science.gov (United States)

    Bortolin, Raul Hernandes; da Graça Azevedo Abreu, Bento João; Abbott Galvão Ururahy, Marcela; Costa de Souza, Karla Simone; Bezerra, João Felipe; Loureiro, Melina Bezerra; da Silva, Flávio Santos; Marques, Dáfiny Emanuele da Silva; Batista, Angélica Amanda de Sousa; Oliveira, Gisele; Luchessi, André Ducati; Lima, Valéria Morgiana Gualberto Duarte Moreira; Miranda, Carlos Eduardo Saraiva; Lia Fook, Marcus Vinicius; Almeida, Maria das Graças; de Rezende, Luciana Augusto; de Rezende, Adriana Augusto

    2015-01-01

    Several studies have established an association between diabetes and alterations in bone metabolism; however, the underlying mechanism is not well established. Although zinc is recognized as a potential preventive agent against diabetes-induced bone loss, there is no evidence demonstrating its effect in chronic diabetic conditions. This study evaluated the effects of zinc supplementation in a chronic (90 days) type 1 diabetes-induced bone-loss model. Male Wistar rats were distributed in three groups: control, type 1 diabetes mellitus (T1DM), and T1DM plus zinc supplementation (T1DMS). Serum biochemical analysis; tibia histomorphometric, biomechanical, and collagen-content analyses; and femur mRNA expression were evaluated. Relative to T1DM, the zinc-supplemented group showed increased histomorphometric parameters such as TbWi and BAr and decreased TbSp, increased biomechanical parameters (maximum load, stiffness, ultimate strain, and Young's modulus), and increased type I collagen content. Interestingly, similar values for these parameters were observed between the T1DMS and control groups. These results demonstrate the protective effect of zinc on the maintenance of bone strength and flexibility. In addition, downregulation of OPG, COL1A, and MMP-9 genes was observed in T1DMS, and the anabolic effects of zinc were evidenced by increased OC expression and serum ALP activity, both related to osteoblastogenesis, demonstrating a positive effect on bone formation. In contrast, T1DM showed excessive bone loss, observed through reduced histomorphometric and biomechanical parameters, characterizing diabetes-associated bone loss. The bone loss was also observed through upregulation of OPG, COL1A, and MMP-9 genes. In conclusion, zinc showed a positive effect on the maintenance of bone architecture and biomechanical parameters. Indeed, OC upregulation and control of expression of OPG, COL1A, and MMP-9 mRNAs, even in chronic hyperglycemia, support an anabolic and protective

  6. Tidal Constraints on Planetary Habitability

    CERN Document Server

    Barnes, Rory; Greenberg, Richard; Raymond, Sean N; Heller, Rene

    2009-01-01

    We review how tides may impact the habitability of terrestrial-like planets. If such planets form around low-mass stars, then planets in the circumstellar habitable zone will be close enough to their host stars to experience strong tidal forces. We discuss 1) decay of semi-major axis, 2) circularization of eccentric orbits, 3) evolution toward zero obliquity, 4) fixed rotation rates (not necessarily synchronous), and 5) internal heating. We briefly describe these effects using the example of a 0.25 solar mass star with a 10 Earth-mass companion. We suggest that the concept of a habitable zone should be modified to include the effects of tides.

  7. Observation of a tidal effect on the Polar Jet Stream

    Directory of Open Access Journals (Sweden)

    C. H. Best

    2015-08-01

    Full Text Available Variations in the Polar Jet Stream directly affect weather across Europe and North America (Francis et al., 2012. Jet Stream dynamics are governed by the development of planetary Rossby waves (Dickinson, 1978 driven by variation of the Coriolis force with latitude. Here we show that increasing atmospheric tides induce the development of Rossby waves, especially during winter months. This changes the flow and direction of the Jet Stream, as measured by the Arctic Oscillation (AO. Although horizontal tidal forces are tiny (107 smaller than gravity, they act over huge areas dragging the Jet Stream flow southwards in regular pulses as the earth rotates. This induces a changing Coriolis torque, which then distorts the Jet Stream flow. The data from eight recent winters are studied indicating that the AO is anti-correlated to the horizontal "tractional" component of tides acting between latitude 45 and 60° N. The observed 28 day cycle in Jet Stream flow and extent has a statistical significance > 99 %. A cross-correlation between all daily AO data since 1950 and the tractional tidal strength shows a significant anti-correlation with a lag time of ~ 5 days. The strongest correlation and largest excursions of the AO are observed during winter 2005/2006 – a maximum lunar standstill year. This declination dependence of tidal forces at high latitudes is the proposed cause of many previous reports of an 18.6 year dependence of continental rainfall and drought.

  8. Shoemaker-Levy 9 and the tidal disruption of comets

    Science.gov (United States)

    Benz, W.; Asphaug, E.

    1994-01-01

    The break-up of Periodic Comet Shoemaker-Levy 9 into multiple pieces following its grazing encounter with Jupiter in July 1992 can be used to study tidally-induced fracture in comets. This spectacular event allows us not only to set limits on the size, strength and density of Shoemaker-Levy 9 itself, but provides invaluable guidance to numerical modeling of such encounters. In an extensive treatment of tidal breakup which assumed self-gravitating, homogeneous, perfectly elastic bodies, Dobrovolskis derived simple analytical expressions for the tidally-induced surface and central stresses. Both can be cast in such a way that Poisson's ratio is the only material dependent constant entering these expressions. Whether both surface and central failure must be initiated as a criterion for breakup, or either one of them is sufficient, remains a subject of disagreement. To resolve this debate, we model the details of cometary breakup using a three-dimensional Smooth Particle Hydrodynamics (SPH) code modified to simulate fracture in small solid objects. At lower stresses associated with brittle failure, we use a rate-dependent strength based on the nucleation of incipient flaws whose number density is given by a Weibull distribution.

  9. Large-Scale Structure and Gravitational Waves III: Tidal Effects

    CERN Document Server

    Schmidt, Fabian; Zaldarriaga, Matias

    2013-01-01

    The leading locally observable effect of a long-wavelength metric perturbation corresponds to a tidal field. We derive the tidal field induced by scalar, vector, and tensor perturbations, and use second order perturbation theory to calculate the effect on the locally measured small-scale density fluctuations. For sub-horizon scalar perturbations, we recover the standard perturbation theory result ($F_2$ kernel). For tensor modes of wavenumber $k_L$, we find that effects persist for $k_L\\tau \\gg 1$, i.e. even long after the gravitational wave has entered the horizon and redshifted away, i.e. it is a "fossil" effect. We then use these results, combined with the "ruler perturbations" of arXiv:1204.3625, to predict the observed distortion of the small-scale matter correlation function induced by a long-wavelength tensor mode. We also estimate the observed signal in the B mode of the cosmic shear from a gravitational wave background, including both tidal (intrinsic alignment) and projection (lensing) effects. The ...

  10. Tidal disruption events from supermassive black hole binaries

    CERN Document Server

    Coughlin, Eric R; Nixon, Chris; Begelman, Mitchell C

    2016-01-01

    We investigate the pre-disruption gravitational dynamics and post-disruption hydrodynamics of the tidal disruption of stars by supermassive black hole (SMBH) binaries. We focus on binaries with relatively low mass primaries ($10^6M_{\\odot}$), moderate mass ratios, and separations with reasonably long gravitational wave inspiral times (tens of Myr). First, we generate a large ensemble (between 1 and 10 million) of restricted three-body integrations to quantify the statistical properties of tidal disruptions by circular SMBH binaries of initially-unbound stars. Compared to the reference case of a disruption by a single SMBH, the binary potential induces significant variance into the specific energy and angular momentum of the star at the point of disruption. Second, we use Newtonian numerical hydrodynamics to study the detailed evolution of the fallback debris from 120 disruptions randomly selected from the three-body ensemble (excluding only the most deeply penetrating encounters). We find that the overall mor...

  11. Frequency interpretation of tidal peak in intracranial pressure wave.

    Science.gov (United States)

    Shahsavari, Sima; McKelvey, Tomas

    2008-01-01

    A new approach to locate different components of ICP signal for each cardiac induced ICP beat is presented. In this method an initial timing map is used to define the appropriate part of the ICP wave which should be searched for the specific component. In parallel a recently proposed method was used to decompose the ICP wave to its different frequency harmonics. This algorithm, which is based on tracking the amplitude of the harmonic components using Kalman filtering, brings both heart rate variability and cardiorespiratory interaction into account and provides good time and frequency resolution. Comparing the results of two methods for seventeen ICP records, each one hour long, it has been observed that the fundamental cardiac component has the most significant contribution in the construction of the tidal peak in ICP and therefore tracking of this harmonic could be informative of the tidal peak evolution over the time.

  12. Tidal Tales of Minor Mergers: Star Formation in the Tidal Debris of Minor Mergers

    CERN Document Server

    Knierman, Karen A

    2009-01-01

    How does the tidal debris of minor galaxy mergers contribute to structures in spiral galaxies or in the intergalactic medium? While major mergers are known to create structures such as tidal dwarf galaxies and star clusters within their tidal debris, less is known about minor mergers (mass ratios between a dwarf galaxy and disk galaxy of less than one-third) and their tidal debris. This work surveys 6 nearby minor mergers using optical broad-band and H-alpha narrow-band imaging to characterize star formation in their tidal debris. Young star clusters with ages less than the dynamical age of the tidal tails are found in all 6 mergers, indicating that the star clusters formed in situ. Even if minor mergers contribute less tidal debris per interaction than major mergers, they are more common and possibly contribute structure to all types of galaxies and to the intergalactic medium throughout the history of the universe.

  13. Diffuser Augmented Horizontal Axis Tidal Current Turbines

    Directory of Open Access Journals (Sweden)

    Nasir Mehmood

    2012-09-01

    Full Text Available The renewal energy technologies are increasingly popular to ensure future energy sustenance and address environmental issues. The tides are enormous and consistent untapped resource of renewable energy. The growing interest in exploring tidal energy has compelling reasons such as security and diversity of supply, intermittent but predictable and limited social and environmental impacts. The tidal energy industry is undergoing an increasing shift towards diffuser augmented turbines. The reason is the higher power output of diffuser augmented turbines compared to conventional open turbines. The purpose of this study is to present a comprehensive review of diffuser augmented horizontal axis tidal current turbines. The components, relative advantages, limitations and design parameters of diffuser augmented horizontal axis tidal current turbines are presented in detail. CFD simulation of NACA 0016 airfoil is carried out to explore its potential for designing a diffuser. The core issues associated with diffuser augmented horizontal axis tidal current turbines are also discussed.

  14. Relativistic theory of tidal Love numbers

    CERN Document Server

    Binnington, Taylor

    2009-01-01

    In Newtonian gravitational theory, a tidal Love number relates the mass multipole moment created by tidal forces on a spherical body to the applied tidal field. The Love number is dimensionless, and it encodes information about the body's internal structure. We present a relativistic theory of Love numbers, which applies to compact bodies with strong internal gravities; the theory extends and completes a recent work by Flanagan and Hinderer, which revealed that the tidal Love number of a neutron star can be measured by Earth-based gravitational-wave detectors. We consider a spherical body deformed by an external tidal field, and provide precise and meaningful definitions for electric-type and magnetic-type Love numbers; and these are computed for polytropic equations of state. The theory applies to black holes as well, and we find that the relativistic Love numbers of a nonrotating black hole are all zero.

  15. Preliminary correlations of feature strength in spark-induced breakdown spectroscopy of bioaerosols with concentrations measured in laboratory analyses

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Morgan S.; Bauer, Amy J. Ray

    2010-05-01

    We present preliminary results that show good correlation between elemental compositions of three bioaerosol samples, as measured in the laboratory by combustion analysis and with proton-induced x-ray emission and spark-induced breakdown spectroscopy signals integrated over the entire emission time profiles. Atomic (Ca, Al, Fe, and Si) and molecular features (CN, N2{sup +}, and OH) were observed compared to the laboratory data.

  16. Synchrotron radiation structure analyses of the light-induced radical pair of a hexaarylbiimidazolyl derivative. Origin of the spin-multiplicity change

    CERN Document Server

    Kawano, M; Matsubara, K; Imabayashi, H; Mitsumi, M; Toriumi, K; Ohashi, Y

    2002-01-01

    In situ synchrotron radiation structure analyses of a light-induced radical pair from o-Cl-HABI were performed by using an X-ray vacuum camera at 23-70K at the BL02B1 station of SPring-8. The combined results of X-ray analysis with theoretical calculation, IR, and UV-vis spectroscopy reveal that a slight conformational change of the radical pair causes the drastic spin-multiplicity change during 2-140K. (author)

  17. Is there evidence of adaptation to tidal flooding in saplings of baldcypress subjected to different salinity regimes?

    Science.gov (United States)

    Krauss, K.W.; Doyle, T.W.; Howard, R.J.

    2009-01-01

    Plant populations may adapt to environmental conditions over time by developing genetically based morphological or physiological characteristics. For tidal freshwater forested wetlands, we hypothesized that the conditions under which trees developed led to ecotypic difference in response of progeny to hydroperiod. Specifically, we looked for evidence of ecotypic adaptation for tidal flooding at different salinity regimes using growth and ecophysiological characteristics of two tidal and two non-tidal source collections of baldcypress (Taxodium distichum (L.) L.C. Rich) from the southeastern United States. Saplings were subjected to treatments of hydrology (permanent versus tidal flooding) and salinity (0 versus ???2 g l-1) for two and a half growing seasons in a greenhouse environment. Saplings from tidal sources maintained 21-41% lower overall growth and biomass accumulation than saplings from non-tidal sources, while saplings from non-tidal sources maintained 14-19% lower overall rates of net photosynthetic assimilation, leaf transpiration, and stomatal conductance than saplings from tidal sources. However, we found no evidence for growth or physiological enhancement of saplings from tidal sources to tide, or of saplings from non-tidal sources to no tide. All saplings growing under permanent flooding exhibited reduced growth and leaf gas exchange regardless of source, with little evidence for consistent salinity effects across hydroperiods. While we reject our original hypothesis, we suggest that adaptations of coastal baldcypress to broad (rather than narrow) environmental conditions may promote ecophysiological and growth enhancements under a range of global-change-induced stressors, perhaps reflecting a natural resilience to environmental change while precluding adaptations for specific flood regimes.

  18. Tenants at-risk-of-poverty induced by housing expenditure – exploratory analyses with EU-SILC

    NARCIS (Netherlands)

    Haffner, M.E.A.; Dol, C.P.; Heylen, K.

    2014-01-01

    Combating poverty and social exclusion is a core policy issue in the European Union (EU). The Statis-tics on Income and Living Conditions (EU-SILC) database facilitates analyses of the extent of poverty and social exclusion. One of the indicators built from the database is the at-risk-of-poverty ind

  19. Effect of tidal fluctuations on transient dispersion of simulated contaminant concentrations in coastal aquifers

    Science.gov (United States)

    La Licata, Ivana; Langevin, Christian D.; Dausman, Alyssa M.; Alberti, Luca

    2013-01-01

    Variable-density groundwater models require extensive computational resources, particularly for simulations representing short-term hydrologic variability such as tidal fluctuations. Saltwater-intrusion models usually neglect tidal fluctuations and this may introduce errors in simulated concentrations. The effects of tides on simulated concentrations in a coastal aquifer were assessed. Three analyses are reported: in the first, simulations with and without tides were compared for three different dispersivity values. Tides do not significantly affect the transfer of a hypothetical contaminant into the ocean; however, the concentration difference between tidal and non-tidal simulations could be as much as 15%. In the second analysis, the dispersivity value for the model without tides was increased in a zone near the ocean boundary. By slightly increasing dispersivity in this zone, the maximum concentration difference between the simulations with and without tides was reduced to as low as 7%. In the last analysis, an apparent dispersivity value was calculated for each model cell using the simulated velocity variations from the model with tides. Use of apparent dispersivity values in models with a constant ocean boundary seems to provide a reasonable approach for approximating tidal effects in simulations where explicit representation of tidal fluctuations is not feasible.

  20. Estimating Coastal Lagoon Tidal Flooding and Repletion with Multidate ASTER Thermal Imagery

    Directory of Open Access Journals (Sweden)

    Thomas R. Allen

    2012-10-01

    Full Text Available Coastal lagoons mix inflowing freshwater and tidal marine waters in complex spatial patterns. This project sought to detect and measure temperature and spatial variability of flood tides for a constricted coastal lagoon using multitemporal remote sensing. Advanced Spaceborne Thermal Emission Radiometer (ASTER thermal infrared data provided estimates of surface temperature for delineation of repletion zones in portions of Chincoteague Bay, Virginia. ASTER high spatial resolution sea-surface temperature imagery in conjunction with in situ observations and tidal predictions helped determine the optimal seasonal data for analyses. The selected time series ASTER satellite data sets were analyzed at different tidal phases and seasons in 2004–2006. Skin surface temperatures of ocean and estuarine waters were differentiated by flood tidal penetration and ebb flows. Spatially variable tidal flood penetration was evaluated using discrete seed-pixel area analysis and time series Principal Components Analysis. Results from these techniques provide spatial extent and variability dynamics of tidal repletion, flushing, and mixing, important factors in eutrophication assessment, water quality and resource monitoring, and application of hydrodynamic modeling for coastal estuary science and management.

  1. A STUDY ON EQUILIBRIUM COASTAL PROFILES OF THE CLOSE TIDAL FLAT—A Case Study of Fengxian Tidal Flat

    Institute of Scientific and Technical Information of China (English)

    LIHeng-peng; YANGGui-shan

    2002-01-01

    The article analyses the temporal-spatial changes of profiles by EOF(Emipirical Orthogonal Function)analysis and DTM analysis of GIS.These profiles,which are not affected by engineering,are chosen from the coast with successive field monitoring data from 1990 to 1999.Temporal and spatial EOF indicates the obvious stability of coast profile paramclino with steep slopes flat.In spatial scale,high tidal flats and deep-water terraces are in a balance state while upper clino with steep slopes are sensitive and the stability is easy to be destroyes.In temporal scale,the erosion and deposition in this area are kepy in balance in a whole.There are almost no change below -8-9.5m.At the same time,it is the lower limit of tidal affection and the erosion and deposition process from it to high tidal flat keep in balance for many years.So the closre depth is appointed to from -8m to -9.5m(Wusong datum mark).

  2. Tidal river dynamics: Implications for deltas

    Science.gov (United States)

    Hoitink, A. J. F.; Jay, D. A.

    2016-03-01

    Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology. It is only in the last few decades that substantial research efforts have been focused on the interactions of river discharge with tidal waves and storm surges into regions beyond the limit of salinity intrusion, a realm that can extend inland hundreds of kilometers. One key phenomenon resulting from this interaction is the emergence of large fortnightly tides, which are forced long waves with amplitudes that may increase beyond the point where astronomical tides have become extinct. These can be larger than the linear tide itself at more landward locations, and they greatly influence tidal river water levels and wetland inundation. Exploration of the spectral redistribution and attenuation of tidal energy in rivers has led to new appreciation of a wide range of consequences for fluvial and coastal sedimentology, delta evolution, wetland conservation, and salinity intrusion under the influence of sea level rise and delta subsidence. Modern research aims at unifying traditional harmonic tidal analysis, nonparametric regression techniques, and the existing understanding of tidal hydrodynamics to better predict and model tidal river dynamics both in single-thread channels and in branching channel networks. In this context, this review summarizes results from field observations and modeling studies set in tidal river environments as diverse as the Amazon in Brazil, the Columbia, Fraser and Saint Lawrence in North America, the Yangtze and Pearl in China, and the Berau and Mahakam in Indonesia. A description of state-of-the-art methods for a comprehensive analysis of water levels, wave propagation, discharges, and inundation extent in tidal rivers is provided. Implications for lowland river deltas are also discussed in terms of sedimentary deposits, channel bifurcation, avulsion, and salinity intrusion, addressing contemporary research challenges.

  3. Eicosapentaenoic acid prevents high fat diet-induced metabolic disorders: Genomic and metabolomic analyses of underlying mechanism

    Science.gov (United States)

    Previously our lab demonstrated eicosapenaenoic acid (EPA)'s ability to prevent high-fat (HF) diet-induced obesity by decreasing insulin resistance, glucose intolerance and inflammation. In the current study, we used genomic and metabolomic approaches to further investigate the molecular basis for t...

  4. Counter rotating type hydroelectric unit suitable for tidal power station

    Energy Technology Data Exchange (ETDEWEB)

    Kanemoto, T [Faculty of Engineering, Kyushu Institute of Technology, Sensui 1-1, Tobata, Kitakyushu 804-8550 (Japan); Suzuki, T, E-mail: turbo@tobata.isc.kyutech.ac.j [Graduate School of Engineering, Kyushu Institute of Technology, Sensui 1-1, Tobata, Kitakyushu 804-8550 (Japan)

    2010-08-15

    The counter rotating type hydroelectric unit, which is composed of the axial flow type tandem runners and the peculiar generator with double rotational armatures,was proposed to utilize effectively the tidal power. In the unit, the front and the rear runners counter drive the inner and the outer armatures of the generator, respectively. Besides, the flow direction at the rear runner outlet must coincide with the flow direction at the front runner inlet, because the angular momentum through the rear runner must coincides with that through the front runner. That is, the flow runs in the axial direction at the rear runner outlet while the axial inflow at the front runner inlet. Such operations are suitable for working at the seashore with rising and falling tidal flows, and the unit may be able to take place of the traditional bulb type turbines. The tandem runners were operated at the on-cam conditions, in keeping the induced frequency constant. The output and the hydraulic efficiency are affected by the adjustment of the front and the blade setting angles. The both optimum angles giving the maximum output and/or efficiency were presented at the various discharges/heads. To promote more the tidal power generation by this type unit, the runners were also modified so as to be suitable for both rising and falling flows. The hydraulic performances are acceptable while the output is determined mainly by the trailing edge profiles of the runner blades.

  5. Are Tidal Effects Responsible for Exoplanetary Spin-Orbit Alignment?

    CERN Document Server

    Li, Gongjie

    2015-01-01

    The obliquities of planet-hosting stars are clues about the formation of planetary systems. Previous observations led to the hypothesis that for close-in giant planets, spin-orbit alignment is enforced by tidal interactions. Here, we examine two problems with this hypothesis. First, Mazeh and coworkers recently used a new technique -- based on the amplitude of starspot-induced photometric variability -- to conclude that spin-orbit alignment is common even for relatively long-period planets, which would not be expected if tides were responsible. We re-examine the data and find a statistically significant correlation between photometric variability and planetary orbital period that is qualitatively consistent with tidal interactions. However it is still difficult to explain quantitatively, as it would require tides to be effective for periods as long as tens of days. Second, Rogers and Lin argued against a particular theory for tidal re-alignment by showing that initially retrograde systems would fail to be re-...

  6. Tidal torques and the clusters of galaxies evolution

    CERN Document Server

    Popolo, A D

    1998-01-01

    We study the effect of tidal torques on the collapse of density peaks through the equations of motion of a shell of barionic matter falling into the central regions of a cluster of galaxies. We calculate the time of collapse of the perturbation taking into account the gravitational interaction of the quadrupole moment of the system with the tidal field of the matter of the neighbouring proto-clusters. We show that within high-density environments, such as rich clusters of galaxies, tidal torques slow down the collapse of low shell and, as a consequence, a reduction in the mass bound to the collapsed perturbation. Moreover, the delay of the collapse produces a tendency for less dense regions to accrete less mass, with respect to a classical spherical model, inducing a biasing of over-dense regions toward higher mass. Finally we calculate the bias coefficient using a selection function properly defined showing that for a Standard Cold Dark Matter (SCDM) model this bias can account for a substantial part of the ...

  7. A quasilocal calculation of tidal heating

    CERN Document Server

    Booth, I S; Booth, Ivan S.; Creighton, Jolien D. E.

    2000-01-01

    We present a method for computing the flux of energy through a closed surfacecontaining a gravitating system. This method, which is based on the quasilocalformalism of Brown and York, is illustrated by two applications: a calculationof (i) the energy flux, via gravitational waves, through a surface nearinfinity and (ii) the tidal heating in the local asymptotic frame of a bodyinteracting with an external tidal field. The second application represents thefirst use of the quasilocal formalism to study a non-stationary spacetime andshows how such methods can be used to study tidal effects in isolatedgravitating systems.

  8. Tidal flow separation at protruding beach nourishments

    OpenAIRE

    Rademacher, Max; de Schipper, Matthieu A.; Swinkels, Cilia; MacMahan, Jamie H.; Reniers, Ad J.H.M.

    2017-01-01

    The article of record as published may be found at http://dx.doi.org/10.1002/2016JC011942 In recent years, the application of large-scale beach nourishments has been discussed, with the Sand Motor in the Netherlands as the first real-world example. Such protruding beach nourishments have an impact on tidal currents, potentially leading to tidal flow separation and the generation of tidal eddies of length scales larger than the nourishment itself. The present study examines the cha...

  9. On the Tidal Dissipation of Obliquity

    CERN Document Server

    Rogers, T M

    2013-01-01

    We investigate tidal dissipation of obliquity in hot Jupiters. Assuming an initial random orientation of obliquity and parameters relevant to the observed population, the obliquity of hot Jupiters does not evolve to purely aligned systems. In fact, the obliquity evolves to either prograde, retrograde or 90^{o} orbits where the torque due to tidal perturbations vanishes. This distribution is incompatible with observations which show that hot jupiters around cool stars are generally aligned. This calls into question the viability of tidal dissipation as the mechanism for obliquity alignment of hot Jupiters around cool stars.

  10. Distribution of iron- and sulfate-reducing bacteria across a coastal acid sulfate soil (CASS environment: implications for passive bioremediation by tidal inundation

    Directory of Open Access Journals (Sweden)

    Yu-Chen eLing

    2015-07-01

    Full Text Available Coastal acid sulfate soils (CASS constitute a serious and global environmental problem. Oxidation of iron sulfide minerals exposed to air generates sulfuric acid with consequently negative impacts on coastal and estuarine ecosystems. Tidal inundation represents one current treatment strategy for CASS, with the aim of neutralizing acidity by triggering microbial iron- and sulfate-reduction and inducing the precipitation of iron-sulfides. Although well-known functional guilds of bacteria drive these processes, their distributions within CASS environments, as well as their relationships to tidal cycling and the availability of nutrients and electron acceptors, are poorly understood. These factors will determine the long-term efficacy of passive CASS remediation strategies. Here we studied microbial community structure and functional guild distribution in sediment cores obtained from ten depths ranging from 0-20 cm in three sites located in the supra-, inter- and sub-tidal segments, respectively, of a CASS-affected salt marsh (East Trinity, Cairns, Australia. Whole community 16S rRNA gene diversity within each site was assessed by 454 pyrotag sequencing and bioinformatic analyses in the context of local hydrological, geochemical and lithological factors. The results illustrate spatial overlap, or close association, of iron- and sulfate-reducing bacteria in an environment rich in organic matter and controlled by parameters such as acidity, redox potential, degree of water saturation, and mineralization. The observed spatial distribution implies the need for empirical understanding of the timing, relative to tidal cycling, of various terminal electron-accepting processes that control acid generation and biogeochemical iron and sulfur cycling.

  11. Downstream hydraulic geometry of a tidally influenced river delta

    NARCIS (Netherlands)

    Sassi, M.G.; Hoitink, A.J.F.; Brye, de B.; Deleersnijder, E.

    2012-01-01

    Channel geometry in tidally influenced river deltas can show a mixed scaling behavior between that of river and tidal channel networks, as the channel forming discharge is both of river and tidal origin. We present a method of analysis to quantify the tidal signature on delta morphology, by extendin

  12. Ocean tidal signals in observatory and satellite magnetic measurements

    DEFF Research Database (Denmark)

    Maus, S.; Kuvshinov, A.

    2004-01-01

    Ocean flow moves sea water through the Earth's magnetic field, inducing electric fields, currents and secondary magnetic fields. These motionally induced magnetic fields have a potential for the remote sensing of ocean flow variability. A first goal must be to gain a better understanding of magne......Ocean flow moves sea water through the Earth's magnetic field, inducing electric fields, currents and secondary magnetic fields. These motionally induced magnetic fields have a potential for the remote sensing of ocean flow variability. A first goal must be to gain a better understanding......, and P1 periods turn out to be dominated by unrelated external fields. In contrast, observed lunar M2 and N2 tidal signals are in fair agreement with predictions from motional induction. The lunar diurnal O1 signal, visible at some observatories, could be caused by ocean flow but disagrees in amplitude...

  13. Hydrodynamics and sediment suspension in shallow tidal channels intersecting a tidal flat

    Science.gov (United States)

    Pieterse, Aline; Puleo, Jack A.; McKenna, Thomas E.

    2016-05-01

    A field study was conducted on a tidal flat intersected by small tidal channels (depth stress and turbulent kinetic energy were computed from high frequency velocity measurements. Maximum water depth at the field site varied from 0.11 m during the lowest neap high tide to 0.58 m during a storm event. In the channel intersecting the tidal flat, the shear stress, turbulence and along-channel velocity were ebb dominant; e.g. 0.33 m/s peak velocity for ebb compared to 0.19 m/s peak velocity for flood. Distinct pulses in velocity occurred when the water level was near the tidal flat level. The velocity pulse during flood tide occurred at a higher water level than during ebb tide. No corresponding velocity pulse on the tidal flat was observed. Sediment concentrations peaked at the beginning and end of each tidal cycle, and often had a secondary peak close to high tide, assumed to be related to sediment advection. The influence of wind waves on bed shear stress and sediment suspension was negligible. Water levels were elevated during a storm event such that the tidal flat remained inundated for 4 tidal cycles. The water did not drain from the tidal flat into the channels during the storm, and no velocity pulses occurred. Along-channel velocities, turbulent kinetic energy, and shear stresses were therefore smaller in the channels during storm conditions than during non-storm conditions.

  14. Genetic and molecular analysis of radon-induced rat lung tumours; Analyse cytogenetique et moleculaire des tumeurs pulmonaires radon-induites chez le rat

    Energy Technology Data Exchange (ETDEWEB)

    Guilly, M.N.; Joubert, Ch.; Levalois, C.; Dano, L.; Chevillard, S. [CEA Fontenay-aux-Roses, Dept. de Radiobiologie et de Radiopathologie, 92 (France)

    2002-03-01

    We have a model of radon-induced rat lung tumours, which allow us to analyse the cytogenetic and molecular alterations of the tumours. The aim is to better understand the mechanisms of radio-induced carcinogenesis and to define if it exists a specificity of radio-induced genetic alterations as compared to the genetic alterations found in the sporadic tumours. We have started our analysis by developing global cytogenetic and molecular approaches. We have shown that some alterations are recurrent. The genes that are potentially involved are the oncogene MET and the tumour suppressor Bene p16, which are also frequently altered in human lung tumours. Simultaneously, we have focussed our analysis by targeting the search of mutation in the tumour suppressor gene TP3. We have found that 8 of 39 tumours were mutated by deletion in the coding sequence of TP53. This high frequency of deletion, which is not observed in the human p53 mutation database could constitute a signature of radio-induced alterations. On this assumption, this type of alteration should not be only found on TP53 Bene but also in other suppressor genes which are inactivated by a mutation such as p16 for example. The work we are carrying out on radio-induced tumours among humans and animals is directed to this end. (author)

  15. Tidal Response of Preliminary Jupiter Model

    OpenAIRE

    Wahl, Sean M; Hubbard, Willam B.; Militzer, Burkhard

    2016-01-01

    In anticipation of improved observational data for Jupiter's gravitational field from the Juno spacecraft, we predict the static tidal response for a variety of Jupiter interior models based on ab initio computer simulations of hydrogen-helium mixtures. We calculate hydrostatic-equilibrium gravity terms using the non-perturbative concentric Maclaurin Spheroid (CMS) method that eliminates lengthy expansions used in the theory of figures. Our method captures terms arising from the coupled tidal...

  16. Applying genotyping (TILLING and phenotyping analyses to elucidate gene function in a chemically induced sorghum mutant population

    Directory of Open Access Journals (Sweden)

    Franks Cleve

    2008-10-01

    Full Text Available Abstract Background Sorghum [Sorghum bicolor (L. Moench] is ranked as the fifth most important grain crop and serves as a major food staple and fodder resource for much of the world, especially in arid and semi-arid regions. The recent surge in sorghum research is driven by its tolerance to drought/heat stresses and its strong potential as a bioenergy feedstock. Completion of the sorghum genome sequence has opened new avenues for sorghum functional genomics. However, the availability of genetic resources, specifically mutant lines, is limited. Chemical mutagenesis of sorghum germplasm, followed by screening for mutants altered in important agronomic traits, represents a rapid and effective means of addressing this limitation. Induced mutations in novel genes of interest can be efficiently assessed using the technique known as Targeting Induced Local Lesion IN Genomes (TILLING. Results A sorghum mutant population consisting of 1,600 lines was generated from the inbred line BTx623 by treatment with the chemical agent ethyl methanesulfonate (EMS. Numerous phenotypes with altered morphological and agronomic traits were observed from M2 and M3 lines in the field. A subset of 768 mutant lines was analyzed by TILLING using four target genes. A total of five mutations were identified resulting in a calculated mutation density of 1/526 kb. Two of the mutations identified by TILLING and verified by sequencing were detected in the gene encoding caffeic acid O-methyltransferase (COMT in two independent mutant lines. The two mutant lines segregated for the expected brown midrib (bmr phenotype, a trait associated with altered lignin content and increased digestibility. Conclusion TILLING as a reverse genetic approach has been successfully applied to sorghum. The diversity of the mutant phenotypes observed in the field, and the density of induced mutations calculated from TILLING indicate that this mutant population represents a useful resource for members of

  17. On the Timing of Foraging Flights by Oystercatchers, Haematopus ostralegus, on Tidal Mudflats

    NARCIS (Netherlands)

    Daan, Serge; Koene, Paul

    1981-01-01

    The tidal movements of flocks of oystercatchers foraging on mudflats at low tide and roosting inland behind a dike at high tide were studied and the effects of day-to-day variations in the time of mudflat exposure by ebb analysed. High mean water levels and short low tides led to reduced intake duri

  18. Barotropic tidal model for the Bombay High, Gulf of Khambhat and surrounding areas

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.; Shetye, S.R.; Michael, G.S.

    tide along its open boundary, which runs approximately parallel to the 200 m isobath, based on the results from global tidal models. Results of a month long simulation are analysed harmonically to separate the major constituents, namely, M sub(2), S sub...

  19. Assessment of Soil Quality of Tidal Marshes in Shanghai City

    Institute of Scientific and Technical Information of China (English)

    Qing; WANG; Juan; TAN; Jianqiang; WU; Chenyan; SHA; Junjie; RUAN; Min; WANG; Shenfa; HUANG

    2013-01-01

    We take three types of tidal marshes in Shanghai City as the study object:tidal marshes in mainland,tidal marshes in the rim of islands,and shoal in Yangtze estuary.On the basis of assessing nutrient quality and environmental quality,respectively,we use soil quality index(SQI)to assess the soil quality of tidal flats,meanwhile formulate the quality grading standards,and analyze the current situation and characteristics of it.The results show that except the north of Hangzhou Bay,Nanhui and Jiuduansha with low soil nutrient quality,there are not obvious differences in soil nutrient quality between other regions;the heavy metal pollution of tidal marshes in mainland is more serious than that of tidal marshes in the rim of islands;in terms of the comprehensive soil quality index,the regions are sequenced as follows:Jiuduansha wetland>Chongming Dongtan wetland>Nanhui tidal flat>tidal flat on the periphery of Chongming Island>tidal flat on the periphery of Hengsha Island>Pudong tidal flat>Baoshan tidal flat>tidal flat on the periphery of Changxing Island>tidal flat in the north of Hangzhou Bay.Among them,Jiuduansha wetland and Chongming Dongtan wetland have the best soil quality,belonging to class III,followed by Nanhui tidal flat,tidal flat on the periphery of Chongming Island and tidal flat on the periphery of Hengsha Island,belonging to class IV;tidal flat on the periphery of Changxing Island,Pudong tidal flat,Baoshan tidal flat and tidal flat in the north of Hangzhou Bay belong to class V.

  20. VISCOELASTIC MODELS OF TIDALLY HEATED EXOMOONS

    Energy Technology Data Exchange (ETDEWEB)

    Dobos, Vera [Konkoly Thege Miklos Astronomical Institute, Research Centre of Astronomy and Earth Sciences, Hungarian Academy of Sciences, H-1121 Konkoly Thege Miklós út 15-17, Budapest (Hungary); Turner, Edwin L., E-mail: dobos@konkoly.hu [Department of Astrophysical Sciences, Princeton University, 08544, 4 Ivy Lane, Peyton Hall, Princeton, NJ (United States)

    2015-05-01

    Tidal heating of exomoons may play a key role in their habitability, since the elevated temperature can melt the ice on the body even without significant solar radiation. The possibility of life has been intensely studied on solar system moons such as Europa or Enceladus where the surface ice layer covers a tidally heated water ocean. Tidal forces may be even stronger in extrasolar systems, depending on the properties of the moon and its orbit. To study the tidally heated surface temperature of exomoons, we used a viscoelastic model for the first time. This model is more realistic than the widely used, so-called fixed Q models because it takes into account the temperature dependence of the tidal heat flux and the melting of the inner material. Using this model, we introduced the circumplanetary Tidal Temperate Zone (TTZ), which strongly depends on the orbital period of the moon and less on its radius. We compared the results with the fixed Q model and investigated the statistical volume of the TTZ using both models. We have found that the viscoelastic model predicts 2.8 times more exomoons in the TTZ with orbital periods between 0.1 and 3.5 days than the fixed Q model for plausible distributions of physical and orbital parameters. The viscoelastic model provides more promising results in terms of habitability because the inner melting of the body moderates the surface temperature, acting like a thermostat.

  1. Viscoelastic Models of Tidally Heated Exomoons

    CERN Document Server

    Dobos, Vera

    2015-01-01

    Tidal heating of exomoons may play a key role in their habitability, since the elevated temperature can melt the ice on the body even without significant solar radiation. The possibility of life is intensely studied on Solar System moons such as Europa or Enceladus, where the surface ice layer covers tidally heated water ocean. Tidal forces may be even stronger in extrasolar systems, depending on the properties of the moon and its orbit. For studying the tidally heated surface temperature of exomoons, we used a viscoelastic model for the first time. This model is more realistic than the widely used, so-called fixed Q models, because it takes into account the temperature dependency of the tidal heat flux, and the melting of the inner material. With the use of this model we introduced the circumplanetary Tidal Temperate Zone (TTZ), that strongly depends on the orbital period of the moon, and less on its radius. We compared the results with the fixed Q model and investigated the statistical volume of the TTZ usi...

  2. Half Moon Cove Tidal Project. Feasibility report

    Energy Technology Data Exchange (ETDEWEB)

    1980-11-01

    The proposed Half Moon Cove Tidal Power Project would be located in a small cove in the northern part of Cobscook Bay in the vicinity of Eastport, Maine. The project would be the first tidal electric power generating plant in the United States of America. The basin impounded by the barrier when full will approximate 1.2 square miles. The average tidal range at Eastport is 18.2 feet. The maximum spring tidal range will be 26.2 feet and the neap tidal range 12.8 feet. The project will be of the single pool-type single effect in which generation takes place on the ebb tide only. Utilizing an average mean tidal range of 18.2 feet the mode of operation enables generation for approximately ten and one-half (10-1/2) hours per day or slightly in excess of five (5) hours per tide. The installed capacity will be 12 MW utilizing 2 to 6 MW units. An axial flow, or Bulb type of turbine was selected for this study.

  3. Can Tidal Current Energy Provide Base Load?

    Directory of Open Access Journals (Sweden)

    Simone Giorgi

    2013-06-01

    Full Text Available Tidal energy belongs to the class of intermittent but predictable renewable energy sources. In this paper, we consider a compact set of geographically diverse locations, which have been assessed to have significant tidal stream energy, and attempt to find the degree to which the resource in each location should be exploited so that the aggregate power from all locations has a low variance. An important characteristic of the locations chosen is that there is a good spread in the peak tidal flow times, though the geographical spread is relatively small. We assume that the locations, all on the island of Ireland, can be connected together and also assume a modular set of tidal turbines. We employ multi-objective optimisation to simultaneously minimise variance, maximise mean power and maximise minimum power. A Pareto front of optimal solutions in the form of a set of coefficients determining the degree of tidal energy penetration in each location is generated using a genetic algorithm. While for the example chosen the total mean power generated is not great (circa 100 MW, the case study demonstrated a methodology that can be applied to other location sets that exhibit similar delays between peak tidal flow times.

  4. An integrated approach for analysing earthquake-induced surface effects: A case study from the Northern Apennines, Italy

    Science.gov (United States)

    Castaldini, D.; Genevois, R.; Panizza, M.; Puccinelli, A.; Berti, M.; Simoni, A.

    This paper illustrates research addressing the subject of the earthquake-induced surface effects by means of a multidisciplinary approach: tectonics, neotectonics, seismology, geology, hydrogeology, geomorphology, soil/rock mechanics have been considered. The research is aimed to verify in areas affected by earthquake-triggered landslides a methodology for the identification of potentially unstable areas. The research was organized according to regional and local scale studies. In order to better emphasise the complexity of the relationships between all the parameters affecting the stability conditions of rock slopes in static and dynamic conditions a new integrated approach, Rock Engineering Systems (RES), was applied in the Northern Apennines. In the paper, the different phases of the research are described in detail and an example of the application of RES method in a sample area is reported. A significant aspect of the study can be seen in its attempt to overcome the exclusively qualitative aspects of research into the relationship between earthquakes and induced surface effects, and to advance the idea of beginning a process by which this interaction can be quantified.

  5. Spatial patterns of tidal heating

    CERN Document Server

    Beuthe, Mikael

    2012-01-01

    In a body periodically strained by tides, heating produced by viscous friction is far from homogeneous. I show here that the distribution of the dissipated power within a spherically stratified body is a linear combination of three angular functions. These angular functions depend only on the tidal potential whereas the radial weights are specified by the internal structure of the body. The 3D problem of predicting spatial patterns of dissipation at all radii is thus reduced to the 1D problem of computing weight functions. I compute spatial patterns in various toy models without assuming a specific rheology: a viscoelastic thin shell stratified in conductive and convective layers, an incompressible homogeneous body and a two-layer model of uniform density with a liquid or rigid core. For a body in synchronous rotation undergoing eccentricity tides, dissipation in a mantle surrounding a liquid core is highest at the poles. Within a softer layer (asthenosphere or icy layer), the same tides generate maximum heat...

  6. Metagenomic analyses of alcohol induced pathogenic alterations in the intestinal microbiome and the effect of Lactobacillus rhamnosus GG treatment.

    Directory of Open Access Journals (Sweden)

    Lara Bull-Otterson

    Full Text Available Enteric dysbiosis plays an essential role in the pathogenesis of alcoholic liver disease (ALD. Detailed characterization of the alterations in the gut microbiome is needed for understanding their pathogenic role in ALD and developing effective therapeutic approaches using probiotic supplementation. Mice were fed liquid Lieber-DeCarli diet without or with alcohol (5% v/v for 6 weeks. A subset of mice were administered the probiotic Lactobacillus rhamnosus GG (LGG from 6 to 8 weeks. Indicators of intestinal permeability, hepatic steatosis, inflammation and injury were evaluated. Metagenomic analysis of the gut microbiome was performed by analyzing the fecal DNA by amplification of the V3-V5 regions of the 16S rRNA gene and large-scale parallel pyrosequencing on the 454 FLX Titanium platform. Chronic ethanol feeding caused a decline in the abundance of both Bacteriodetes and Firmicutes phyla, with a proportional increase in the gram negative Proteobacteria and gram positive Actinobacteria phyla; the bacterial genera that showed the biggest expansion were the gram negative alkaline tolerant Alcaligenes and gram positive Corynebacterium. Commensurate with the qualitative and quantitative alterations in the microbiome, ethanol caused an increase in plasma endotoxin, fecal pH, hepatic inflammation and injury. Notably, the ethanol-induced pathogenic changes in the microbiome and the liver were prevented by LGG supplementation. Overall, significant alterations in the gut microbiome over time occur in response to chronic alcohol exposure and correspond to increases in intestinal barrier dysfunction and development of ALD. Moreover, the altered bacterial communities of the gut may serve as significant therapeutic target for the prevention/treatment of chronic alcohol intake induced intestinal barrier dysfunction and liver disease.

  7. Low-level laser therapy in collagenase-induced Achilles tendinitis in rats: analyses of biochemical and biomechanical aspects.

    Science.gov (United States)

    Marcos, Rodrigo Labat; Leal-Junior, Ernesto Cesar Pinto; Arnold, Gilles; Magnenet, Vincent; Rahouadj, Rachid; Wang, Xiong; Demeurie, Frank; Magdalou, Jacques; de Carvalho, Maria Helena Catelli; Lopes-Martins, Rodrigo Álvaro Brandão

    2012-12-01

    NSAIDs are widely prescribed and used over the years to treat tendon injuries despite its well-known long-term side effects. In the last years several animal and human trials have shown that low-level laser therapy (LLLT) presents modulatory effects on inflammatory markers, however the mechanisms involved are not fully understood. The aim of this study was to evaluate the short-term effects of LLLT or sodium diclofenac treatments on biochemical markers and biomechanical properties of inflamed Achilles tendons. Wistar rats Achilles tendons (n = 6/group) were injected with saline (control) or collagenase at peritendinous area of Achilles tendons. After 1 h animals were treated with two different doses of LLLT (810 nm, 1 and 3 J) at the sites of the injections, or with intramuscular sodium diclofenac. Regarding biochemical analyses, LLLT significantly decreased (p laser-treated groups when compared to collagenase and diclofenac groups. We conclude that LLLT was able to reduce tendon inflammation and to preserve tendon resistance and elasticity.

  8. Rapid Quantitative Analyses of Elements on Herb Medicine and Food Powder Using TEA CO2 Laser-Induced Plasma

    Science.gov (United States)

    Khumaeni, Ali; Ramli, Muliadi; Idris, Nasrullah; Lee, Yong Inn; Kurniawan, Koo Hendrik; Lie, Tjung Jie; Deguchi, Yoji; Niki, Hideaki; Kagawa, Kiichiro

    2009-03-01

    A novel technique for rapid quantitative analyses of elements on herb medicine and food powder has successfully been developed. In this technique, the powder samples were plugged in a small hole (2 mm in diameter and 3 mm in depth) and covered by a metal mesh. The Transversely Excited Atmospheric (TEA) CO2 laser (1500 mJ, 200 ns) was focused on the powder sample surfaces passing through the metal mesh at atmospheric pressure of nitrogen surrounding gas. It is hypothesized that the small hole functions to confine the powder particles and suppresses the blowing-off, while the metal mesh works as the source of electrons to initiate the strong gas breakdown plasma. The confined powder particles are subsequently ablated by the laser irradiation and the ablated particles move into the strong gas breakdown plasma region to be atomized and excited. Using this method, a quantitative analysis of the milk powder sample containing different concentrations of Ca was successfully demonstrated, resulting in a good linear calibration curve with high precision.

  9. FEM modeling and histological analyses on thermal damage induced in facial skin resurfacing procedure with different CO2 laser pulse duration

    Science.gov (United States)

    Rossi, Francesca; Zingoni, Tiziano; Di Cicco, Emiliano; Manetti, Leonardo; Pini, Roberto; Fortuna, Damiano

    2011-07-01

    Laser light is nowadays routinely used in the aesthetic treatments of facial skin, such as in laser rejuvenation, scar removal etc. The induced thermal damage may be varied by setting different laser parameters, in order to obtain a particular aesthetic result. In this work, it is proposed a theoretical study on the induced thermal damage in the deep tissue, by considering different laser pulse duration. The study is based on the Finite Element Method (FEM): a bidimensional model of the facial skin is depicted in axial symmetry, considering the different skin structures and their different optical and thermal parameters; the conversion of laser light into thermal energy is modeled by the bio-heat equation. The light source is a CO2 laser, with different pulse durations. The model enabled to study the thermal damage induced into the skin, by calculating the Arrhenius integral. The post-processing results enabled to study in space and time the temperature dynamics induced in the facial skin, to study the eventual cumulative effects of subsequent laser pulses and to optimize the procedure for applications in dermatological surgery. The calculated data where then validated in an experimental measurement session, performed in a sheep animal model. Histological analyses were performed on the treated tissues, evidencing the spatial distribution and the entity of the thermal damage in the collageneous tissue. Modeling and experimental results were in good agreement, and they were used to design a new optimized laser based skin resurfacing procedure.

  10. Cytological and comparative proteomic analyses on male sterility in Brassica napus L. induced by the chemical hybridization agent monosulphuron ester sodium.

    Directory of Open Access Journals (Sweden)

    Yufeng Cheng

    Full Text Available Male sterility induced by a chemical hybridization agent (CHA is an important tool for utilizing crop heterosis. Monosulphuron ester sodium (MES, a new acetolactate synthase-inhibitor herbicide belonging to the sulphonylurea family, has been developed as an effective CHA to induce male sterility in rapeseed (Brassica napus L.. To understand MES-induced male sterility in rapeseed better, comparative cytological and proteomic analyses were conducted in this study. Cytological analysis indicated that defective tapetal cells and abnormal microspores were gradually generated in the developing anthers of MES-treated plants at various development stages, resulting in unviable microspores and male sterility. A total of 141 differentially expressed proteins between the MES-treated and control plants were revealed, and 131 of them were further identified by MALDI-TOF/TOF MS. Most of these proteins decreased in abundance in tissues of MES-treated rapeseed plants, and only a few increased. Notably, some proteins were absent or induced in developing anthers after MES treatment. These proteins were involved in several processes that may be crucial for tapetum and microspore development. Down-regulation of these proteins may disrupt the coordination of developmental and metabolic processes, resulting in defective tapetum and abnormal microspores that lead to male sterility in MES-treated plants. Accordingly, a simple model of CHA-MES-induced male sterility in rapeseed was established. This study is the first cytological and dynamic proteomic investigation on CHA-MES-induced male sterility in rapeseed, and the results provide new insights into the molecular events of male sterility.

  11. Modelling the transverse distribution of velocity and suspended sediment in tidal estuaries

    Science.gov (United States)

    Huijts, K. M. H.

    2011-01-01

    An estuary is a semi-enclosed coastal body of water which has a free connection with the open sea and within which sea water is measurably diluted with fresh water derived from land drainage. Examples are the Western Scheldt River Estuary and the Chesapeake Bay. Within these environments complex patterns of velocity and suspended sediments are observed in the transversal plane (across-estuary and vertical), and sediments are trapped laterally (across-estuary). The transverse structure of velocity is relevant to the transport of salt, sediment, contaminants, oxygen and other material. High sediment concentrations affect water quality, ecology and wildlife, and may cause siltation of navigation channels and harbors. This work aims at a fundamental understanding of the transverse distributions of estuarine velocity and suspended sediment. The thesis provides two-dimensional (cross-sectional) analytical models to identify the effect of individual forcing mechanisms on the transverse distribution of velocity and suspended sediment in tidally-dominated estuaries. The models are based on the shallow water equations and sediment mass balance. Considered are the residual and the semi-diurnal tidal components of the along-estuary, across-estuary and vertical velocity and of the suspended sediment concentration. The models apply to partially to well-mixed tidal estuaries, relatively uniform along-channel conditions and weakly to moderately nonlinear flow. Horizontal density gradients are prescribed based on numerical or observational data. The analytical flows are decomposed into components induced by individual mechanisms. Considered are tides, horizontal residual density gradients, river discharge, stokes return flow, wind, the earth’s rotation, tidal variations in the across-channel density gradient and channel curvature. In addition, two tidally rectified along-channel residual flow mechanisms are considered, which result from net advection of along-channel tidal

  12. Dynamics of tidal and non-tidal currents along the southwest continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Aruna, C.; Ravichandran, C.; Srinivas, K.; Rasheed, P.A.A.; Lekshmi, S.

    the observed time-series of water level collected during November- December 2005, from four tide gauge stations distributed along the southwest shelf of India. The tidal amplitudes showed a general decrease from north to south. Harmonic analysis of the tidal...

  13. Three-dimensional semi-idealized model for tidal motion in tidal estuaries

    NARCIS (Netherlands)

    Kumar, M.; Schuttelaars, H.M.; Roos, P.C.; Möller, M.

    2015-01-01

    In this paper, a three-dimensional semi-idealized model for tidal motion in a tidal estuary of arbitrary shape and bathymetry is presented. This model aims at bridging the gap between idealized and complex models. The vertical profiles of the velocities are obtained analytically in terms of the firs

  14. Kvalitative analyser ..

    DEFF Research Database (Denmark)

    Boolsen, Merete Watt

    bogen forklarer de fundamentale trin i forskningsprocessen og applikerer dem på udvalgte kvalitative analyser: indholdsanalyse, Grounded Theory, argumentationsanalyse og diskursanalyse......bogen forklarer de fundamentale trin i forskningsprocessen og applikerer dem på udvalgte kvalitative analyser: indholdsanalyse, Grounded Theory, argumentationsanalyse og diskursanalyse...

  15. Quantitative Analyses of Force-Induced Amyloid Formation in Candida albicans Als5p: Activation by Standard Laboratory Procedures.

    Directory of Open Access Journals (Sweden)

    Cho X J Chan

    Full Text Available Candida albicans adhesins have amyloid-forming sequences. In Als5p, these amyloid sequences cluster cell surface adhesins to create high avidity surface adhesion nanodomains. Such nanodomains form after force is applied to the cell surface by atomic force microscopy or laminar flow. Here we report centrifuging and resuspending S. cerevisiae cells expressing Als5p led to 1.7-fold increase in initial rate of adhesion to ligand coated beads. Furthermore, mechanical stress from vortex-mixing of Als5p cells or C. albicans cells also induced additional formation of amyloid nanodomains and consequent activation of adhesion. Vortex-mixing for 60 seconds increased the initial rate of adhesion 1.6-fold. The effects of vortex-mixing were replicated in heat-killed cells as well. Activation was accompanied by increases in thioflavin T cell surface fluorescence measured by flow cytometry or by confocal microscopy. There was no adhesion activation in cells expressing amyloid-impaired Als5pV326N or in cells incubated with inhibitory concentrations of anti-amyloid dyes. Together these results demonstrated the activation of cell surface amyloid nanodomains in yeast expressing Als adhesins, and further delineate the forces that can activate adhesion in vivo. Consequently there is quantitative support for the hypothesis that amyloid forming adhesins act as both force sensors and effectors.

  16. Mitochondrial physiology and gene expression analyses reveal metabolic and translational dysregulation in oocyte-induced somatic nuclear reprogramming.

    Directory of Open Access Journals (Sweden)

    Telma C Esteves

    Full Text Available While reprogramming a foreign nucleus after somatic cell nuclear transfer (SCNT, the enucleated oocyte (ooplasm must signal that biomass and cellular requirements changed compared to the nucleus donor cell. Using cells expressing nuclear-encoded but mitochondria-targeted EGFP, a strategy was developed to directly distinguish maternal and embryonic products, testing ooplasm demands on transcriptional and post-transcriptional activity during reprogramming. Specifically, we compared transcript and protein levels for EGFP and other products in pre-implantation SCNT embryos, side-by-side to fertilized controls (embryos produced from the same oocyte pool, by intracytoplasmic injection of sperm containing the EGFP transgene. We observed that while EGFP transcript abundance is not different, protein levels are significantly lower in SCNT compared to fertilized blastocysts. This was not observed for Gapdh and Actb, whose protein reflected mRNA. This transcript-protein relationship indicates that the somatic nucleus can keep up with ooplasm transcript demands, whilst transcription and translation mismatch occurs after SCNT for certain mRNAs. We further detected metabolic disturbances after SCNT, suggesting a place among forces regulating post-transcriptional changes during reprogramming. Our observations ascribe oocyte-induced reprogramming with previously unsuspected regulatory dimensions, in that presence of functional proteins may no longer be inferred from mRNA, but rather depend on post-transcriptional regulation possibly modulated through metabolism.

  17. Factors affecting the hydrochemistry of a mangrove tidal creek, sepetiba bay, Brazil

    Science.gov (United States)

    Ovalle, A. R. C.; Rezende, C. E.; Lacerda, L. D.; Silva, C. A. R.

    1990-11-01

    We studied the porewater chemistry, and spatial and temporal variation of mangrove creek hydrochemistry. Except for nitrate porewater, the concentrations of nutrients we analysed were higher than for creek water. Groundwater is a source of silica and phosphate, whereas total alkalinity and ammonium are related to mangrove porewater migration to the creek. Open bay waters contribute chlorine, dissolved oxygen and elevated pH. The results also suggest that nitrate is related to nitrification inside the creek. During flood tides, salinity, chlorine, dissolved oxygen and pH increase, whereas total alkalinity decreases. This pattern is reversed at ebb tides. Silica, phosphate, nitrate and ammonium show an erratic behaviour during the tidal cycle. Tidal dynamics, precipitation events and nitrification inside the creek were identified as major control factors and an estimate of tidal exchanges indicate that the system is in an equilibrium state.

  18. Mechanistic Insight into Bunyavirus-Induced Membrane Fusion from Structure-Function Analyses of the Hantavirus Envelope Glycoprotein Gc

    Science.gov (United States)

    Stettner, Eva; Jeffers, Scott Allen; Pérez-Vargas, Jimena; Pehau-Arnaudet, Gerard; Tortorici, M. Alejandra; Jestin, Jean-Luc; England, Patrick; Tischler, Nicole D.; Rey, Félix A.

    2016-01-01

    Hantaviruses are zoonotic viruses transmitted to humans by persistently infected rodents, giving rise to serious outbreaks of hemorrhagic fever with renal syndrome (HFRS) or of hantavirus pulmonary syndrome (HPS), depending on the virus, which are associated with high case fatality rates. There is only limited knowledge about the organization of the viral particles and in particular, about the hantavirus membrane fusion glycoprotein Gc, the function of which is essential for virus entry. We describe here the X-ray structures of Gc from Hantaan virus, the type species hantavirus and responsible for HFRS, both in its neutral pH, monomeric pre-fusion conformation, and in its acidic pH, trimeric post-fusion form. The structures confirm the prediction that Gc is a class II fusion protein, containing the characteristic β-sheet rich domains termed I, II and III as initially identified in the fusion proteins of arboviruses such as alpha- and flaviviruses. The structures also show a number of features of Gc that are distinct from arbovirus class II proteins. In particular, hantavirus Gc inserts residues from three different loops into the target membrane to drive fusion, as confirmed functionally by structure-guided mutagenesis on the HPS-inducing Andes virus, instead of having a single “fusion loop”. We further show that the membrane interacting region of Gc becomes structured only at acidic pH via a set of polar and electrostatic interactions. Furthermore, the structure reveals that hantavirus Gc has an additional N-terminal “tail” that is crucial in stabilizing the post-fusion trimer, accompanying the swapping of domain III in the quaternary arrangement of the trimer as compared to the standard class II fusion proteins. The mechanistic understandings derived from these data are likely to provide a unique handle for devising treatments against these human pathogens. PMID:27783711

  19. Histological and MS spectrometric analyses of the modified tissue of bulgy form tadpoles induced by salamander predation

    Directory of Open Access Journals (Sweden)

    Tsukasa Mori

    2012-02-01

    The rapid induction of a defensive morphology by a prey species in face of a predation risk is an intriguing in ecological context; however, the physiological mechanisms that underlie this phenotypic plasticity remain uncertain. Here we investigated the phenotypic changes shown by Rana pirica tadpoles in response to a predation threat by larvae of the salamander Hynobius retardatus. One such response is the bulgy morph phenotype, a relatively rapid swelling in size by the tadpoles that begins within 4 days and reaches a maximum at 8 to 10 days. We found that although the total volume of bodily fluid increased significantly (P<0.01 in bulgy morph tadpoles, osmotic pressure was maintained at the same level as control tadpoles by a significant increase (P<0.01 in Na and Cl ion concentrations. In our previous report, we identified a novel frog gene named pirica that affects the waterproofing of the skin membrane in tadpoles. Our results support the hypothesis that predator-induced expression of pirica on the skin membrane causes retention of absorbed water. Midline sections of bulgy morph tadpoles showed the presence of swollen connective tissue beneath the skin that was sparsely composed of cells containing hyaluronic acid. Mass spectrographic (LC-MS/MS analysis identified histone H3 and 14-3-3 zeta as the most abundant constituents in the liquid aspirated from the connective tissue of bulgy tadpoles. Immunohistochemistry using antibodies against these proteins showed the presence of non-chromatin associated histone H3 in the swollen connective tissue. Histones and 14-3-3 proteins are also involved in antimicrobial activity and secretion of antibacterial proteins, respectively. Bulgy tadpoles have a larger surface area than controls, and their skin often has bite wounds inflicted by the larval salamanders. Thus, formation of the bulgy morph may also require and be supported by activation of innate immune systems.

  20. On M2 tidal amplitude enhancement in the Taiwan Strait and its asymmetry in the cross-strait direction

    Science.gov (United States)

    Yu, Haiqing; Yu, Huaming; Ding, Yang; Wang, Lu; Kuang, Liang

    2015-10-01

    Enhanced M2 tidal amplitude in the Taiwan Strait (TS) and asymmetric M2 tidal amplitude in the cross-strait direction have been found and reproduced in numerical simulations. In this study, Finite Volume Coastal Ocean Model (FVCOM) is applied to investigate the mechanisms behind these features. Model results show that the linear interaction of waves from the East China Sea (ECS) and the Luzon Strait (LS) can explain the formation of the co-amplitude and co-phase lines of the M2 tide in the nodal point area, while the waves from the ECS dominate the tidal motion in the TS according to a basic linear wave superposition. Model simulation also show that wave reflection and transition occur when the M2 tidal waves from the ECS propagate through the TS and encounter an sharply deepened topography. The interaction of these induced reflection waves and the incident waves from the ECS is the main cause for the enhanced M2 tidal amplitude in the TS. The distribution of the sharply deepened topography, rather than the Coriolis effect, is the main reason for the asymmetry of the M2 tidal amplitude in the cross-strait direction in the TS. These findings provide some references for tidal dynamics in other areas, especially where long waves propagate through the shallow water to the deep sea.

  1. Tidally Heated Terrestrial Exoplanets: Viscoelastic Response Models

    CERN Document Server

    Henning, Wade G; Sasselov, Dimitar D; 10.1088/0004-637X/707/2/1000

    2009-01-01

    Tidal friction in exoplanet systems, driven by orbits that allow for durable nonzero eccentricities at short heliocentric periods, can generate internal heating far in excess of the conditions observed in our own solar system. Secular perturbations or a notional 2:1 resonance between a Hot Earth and Hot Jupiter can be used as a baseline to consider the thermal evolution of convecting bodies subject to strong viscoelastic tidal heating. We compare results first from simple models using a fixed Quality factor and Love number, and then for three different viscoelastic rheologies: the Maxwell body, the Standard Anelastic Solid, and the Burgers body. The SAS and Burgers models are shown to alter the potential for extreme tidal heating by introducing the possibility of new equilibria and multiple response peaks. We find that tidal heating tends to exceed radionuclide heating at periods below 10-30 days, and exceed insolation only below 1-2 days. Extreme cases produce enough tidal heat to initiate global-scale parti...

  2. The tidal tails of NGC 2298

    CERN Document Server

    Balbinot, Eduardo; da Costa, Luiz N; Makler, Martin; Maia, Marcio A G

    2011-01-01

    We present an implementation of the matched-filter technique to detect tidal tails of globular clusters. The method was tested using SDSS data for the globular cluster Palomar 5 revealing its well known tidal tails. We also ran a simulation of a globular cluster with a tidal tail where we successfully recover the tails for a cluster at the same position and with the same characteristics of NGC 2298. Based on the simulation we estimate that the matched-filter increases the contrast of the tail relative to the background of stars by a factor of 2.5 for the case of NGC 2298. We also present the photometry of the globular cluster NGC 2298 using the MOSAIC2 camera installed on the CTIO 4m telescope. The photometry covers ~ 3deg2 reaching V ~ 23. A fit of a King profile to the radial density profile of NGC 2298 shows that this cluster has a tidal radius of 15.91' \\pm 1.07' which is twice as in the literature. The application of the matched-filter to NGC 2298 reveals several extra-tidal structures, including a leadi...

  3. Carbon sequestration by Australian tidal marshes

    KAUST Repository

    Macreadie, Peter I.

    2017-03-10

    Australia\\'s tidal marshes have suffered significant losses but their recently recognised importance in CO2 sequestration is creating opportunities for their protection and restoration. We compiled all available data on soil organic carbon (OC) storage in Australia\\'s tidal marshes (323 cores). OC stocks in the surface 1 m averaged 165.41 (SE 6.96) Mg OC ha-1 (range 14-963 Mg OC ha-1). The mean OC accumulation rate was 0.55 ± 0.02 Mg OC ha-1 yr-1. Geomorphology was the most important predictor of OC stocks, with fluvial sites having twice the stock of OC as seaward sites. Australia\\'s 1.4 million hectares of tidal marshes contain an estimated 212 million tonnes of OC in the surface 1 m, with a potential CO2-equivalent value of $USD7.19 billion. Annual sequestration is 0.75 Tg OC yr-1, with a CO2-equivalent value of $USD28.02 million per annum. This study provides the most comprehensive estimates of tidal marsh blue carbon in Australia, and illustrates their importance in climate change mitigation and adaptation, acting as CO2 sinks and buffering the impacts of rising sea level. We outline potential further development of carbon offset schemes to restore the sequestration capacity and other ecosystem services provided by Australia tidal marshes.

  4. Harnessing Ocean Energy by Tidal Current Technologies

    Directory of Open Access Journals (Sweden)

    Nasir Mehmood

    2012-09-01

    Full Text Available The world is heavily dependent on fossil fuels since most of its energy requirements are fulfilled by conventional methods of burning these fuels. The energy demand is increasing by day with growing population. The energy production by fossil fuels is devastating the environment and survival of life on globe is endangered. The renewal energy technologies are vital to ensure future energy sustenance and environmental issues. Ocean is a vast resource of renewable energy. The technology today makes it possible to extract energy from tides. The growing interest in exploring tidal current technologies has compelling reasons such as security and diversity of supply, intermittent but predictable and limited social and environmental impacts. The purpose of this study is to present a comprehensive review of tidal current technologies to harness ocean energy. The ocean energy resources are presented. The author discusses tidal energy technologies. The tidal current turbines are discussed in detail. The author reviews today’s popular tidal current technologies. The present status of ocean energy development is also reported.

  5. Tidal Response of Preliminary Jupiter Model

    Science.gov (United States)

    Wahl, Sean M.; Hubbard, William B.; Militzer, Burkhard

    2016-11-01

    In anticipation of improved observational data for Jupiter’s gravitational field, from the Juno spacecraft, we predict the static tidal response for a variety of Jupiter interior models based on ab initio computer simulations of hydrogen-helium mixtures. We calculate hydrostatic-equilibrium gravity terms, using the non-perturbative concentric Maclaurin Spheroid method that eliminates lengthy expansions used in the theory of figures. Our method captures terms arising from the coupled tidal and rotational perturbations, which we find to be important for a rapidly rotating planet like Jupiter. Our predicted static tidal Love number, {k}2=0.5900, is ˜10% larger than previous estimates. The value is, as expected, highly correlated with the zonal harmonic coefficient J 2, and is thus nearly constant when plausible changes are made to the interior structure while holding J 2 fixed at the observed value. We note that the predicted static k 2 might change, due to Jupiter’s dynamical response to the Galilean moons, and find reasons to argue that the change may be detectable—although we do not present here a theory of dynamical tides for highly oblate Jovian planets. An accurate model of Jupiter’s tidal response will be essential for interpreting Juno observations and identifying tidal signals from effects of other interior dynamics of Jupiter’s gravitational field.

  6. Analysis and comparison of the tidal gravity observations obtained with LCR-ET20 spring gravimeter

    Institute of Scientific and Technical Information of China (English)

    孙和平; 陈晓东; 刘明; 周百力

    2002-01-01

    Based on the tidal gravity observations recorded with LCR-ET20 spring gravimeter at Wuhan international fundamental tidal gravity station, the characteristics of the ET20 and the atmospheric and oceanic gravity signals are studied systematically by using international standard data pre-processing and analysis methods, and by comparing the results with those obtained using superconducting gravimeter (SG) at same station. The numerical results indicate that the identical tidal gravity parameters same as those with the SG are obtained, the instrument can be used effectively to record temporal change of the gravity field, though the accuracy of the ET20 is one order lower than that of the SG, and has also the large drift induced by the spring creep character.

  7. Tidal Forces in Naked Singularity Backgrounds

    CERN Document Server

    Goel, Akash; Roy, Pratim; Sarkar, Tapobrata

    2015-01-01

    The end stage of a gravitational collapse process can generically result in a black hole or a naked singularity. Here we undertake a comparative analysis of the nature of tidal forces in these backgrounds. The effect of such forces is generically exemplified by the Roche limit, which predicts the distance within which a celestial object disintegrates due to the tidal effects of a second more massive object. In this paper, using Fermi normal coordinates, we numerically compute the Roche limit for a class of non-rotating naked singularity backgrounds, and compare them with known results for Schwarzschild black holes. Our analysis indicates that there might be substantially large deviations in the magnitudes of tidal forces in naked singularity backgrounds, compared to the black hole cases. If observationally established, these can prove to be an effective indicator of the nature of the singularity at a galactic centre.

  8. Tidal response of Europa's subsurface ocean

    Science.gov (United States)

    Karatekin, Özgür; Comblen, Richard; Toubeau, Jonathan; Deleersnijder, Eric; van Hoolst, Tim; Dehant, Veronique

    2010-05-01

    Observations of Cassini and Galileo spacecrafts suggest the presence of subsurface global water oceans under the icy shells of several satellites of Jupiter and Saturn. Previous studies have shown that in the presence of subsurface oceans, time-variable tides cause large periodic surface displacements and that tidal dissipation in the icy shell becomes a major energy source that can affect long-term orbital evolution. However, in most studies so far, the dynamics of these satellite oceans have been neglected. In the present study, we investigate the tidal response of the subsurface ocean of Europa to a time-varying potential. Two-dimensional nonlinear shallow water equations are solved on a sphere by means of a finite element code. The resulting ocean tidal flow velocities and surface displacements will be presented.

  9. Double tidal disruptions in galactic nuclei

    CERN Document Server

    Mandel, Ilya

    2015-01-01

    A star on a nearly radial trajectory approaching a massive black hole (MBH) gets tidally disrupted if it comes sufficiently close to the MBH. Here we explore what happens to binary stars whose centers of mass approach the MBH on nearly radial orbits. The interaction with the MBH often leads to both stars being disrupted in sequence. We argue that such events could produce light curves that are substantially different from those of the single disruptions, with possible features such as two local maxima. Tidal forces from the MBH can also lead the binary components to collide; these merger products can form highly magnetized stars, whose subsequent tidal disruption may enable prompt jet formation.

  10. HI Recycling Formation of Tidal Dwarf Galaxies

    CERN Document Server

    Duc, P A; Duc, Pierre-Alain; Brinks, Elias

    2000-01-01

    Galactic collisions trigger a number of phenomena, such as transportation inward of gas from distances of up to kiloparsecs from the center of a galaxy to the nuclear region, fuelling a central starburst or nuclear activity. The inverse process, the ejection of material into the intergalactic medium by tidal forces, is another important aspect and can be studied especially well through detailed HI observations of interacting systems which have shown that a large fraction of the gaseous component of colliding galaxies can be expelled. Part of this tidal debris might fall back, be dispersed throughout the intergalactic medium or recondense to form a new generation of galaxies: the so-called tidal dwarf galaxies. The latter are nearby examples of galaxies in formation. The properties of these recycled objects are reviewed here and different ways to identify them are reviewed.

  11. Tidal Response of Preliminary Jupiter Model

    CERN Document Server

    Wahl, Sean M; Militzer, Burkhard

    2016-01-01

    In anticipation of improved observational data for Jupiter's gravitational field from the Juno spacecraft, we predict the static tidal response for a variety of Jupiter interior models based on ab initio computer simulations of hydrogen-helium mixtures. We calculate hydrostatic-equilibrium gravity terms using the non-perturbative concentric Maclaurin Spheroid (CMS) method that eliminates lengthy expansions used in the theory of figures. Our method captures terms arising from the coupled tidal and rotational perturbations, which we find to be important for a rapidly-rotating planet like Jupiter. Our predicted static tidal Love number $k_2 = 0.5900$ is $\\sim$10\\% larger than previous estimates. The value is, as expected, highly correlated with the zonal harmonic coefficient $J_2$, and is thus nearly constant when plausible changes are made to interior structure while holding $J_2$ fixed at the observed value. We note that the predicted static $k_2$ might change due to Jupiter's dynamical response to the Galilea...

  12. Joule Heating, Particle Precipitation and Dynamical Heating as Possible Tidal Sources in the Antarctic Winter Lower Thermosphere

    Science.gov (United States)

    Fong, W.; Chu, X.; Lu, X.; Chen, C.; Yu, Z.; Fuller-Rowell, T. J.; Richmond, A. D.; Codrescu, M.

    2014-12-01

    Winter temperature tides observed by lidar at McMurdo (77.8°S, 166.7°E), Antarctica, show less than 3 K diurnal and semidiurnal tidal amplitude below 100 km. However, above 100 km, the diurnal and semidiurnal tidal amplitudes grow super-exponentially and can reach at least 15 K near 110 km, which are exceeding that of the freely propagating tides originating from the lower atmosphere. Such fast growth exists for all Kp index cases and diurnal amplitude increases to 15-30 K at 110 km with larger Kp indices corresponding to larger tidal amplitudes and faster growth rates. Combining with the slopes of diurnal tidal phases being steeper above 100 km, and the tidal phases barely changing with altitude from 100 to 106 km, it indicates that in-situ tidal sources may exist near or above 100 km. In this paper, we utilize the coupled thermosphere ionosphere plasmasphere electrodynamics (CTIPe) model to investigate possible sources/mechanisms that lead to the fast amplitude growth of tides in the polar winter region. Joule heating, particle precipitation, and dynamical heating are likely to be the dominant thermospheric tidal sources, according to CTIPe model. Interestingly, the CTIPe tidal amplitudes induced by these sources form a concentric pattern with its center located at the geomagnetic pole, implying that the geomagnetic activity may play an important role. Furthermore, dynamical heating, which includes adiabatic heating/cooling and vertical advection, is likely to be the explanation of the fast growth of diurnal tidal amplitudes even under quiet condition of geomagnetic activity as observed by lidar. We also found that the tides propagating from the lower atmosphere is a minor factor for the fast increase of thermospheric diurnal tides in Antarctica.

  13. The assessment of extactable tidal energy and the effect of tidal energy turbine deployment on the hydrodynamics in Zhoushan

    Institute of Scientific and Technical Information of China (English)

    HOU Fang; BAO Xianwen; LI Benxia; LIU Qianqian

    2015-01-01

    In this study, we construct one 2–dimensional tidal simulation, using an unstructured Finite Volume Coastal Ocean Model (FVCOM). In the 2–D model, we simulated the tidal turbines through adding additional bottom drag in the element where the tidal turbines reside. The additional bottom drag was calculated from the relationship of the bottom friction dissipation and the rated rotor efficiency of the tidal energy turbine. This study analyzed the effect of the tidal energy turbine to the hydrodynamic environment, and calculated the amount of the extractable tidal energy resource at the Guishan Hangmen Channel, considering the rotor wake effect.

  14. The role of tidal-velocity asymmetries in the deposition of silty tidal rhythmites (Carboniferous, Eastern Interior Coal Basin, U.S.A.)

    Energy Technology Data Exchange (ETDEWEB)

    Archer, A.W. [Kansas State Univ., Manhattan, KS (United States). Dept. of Geology; Kuecher, G.J. [Argonne National Lab., IL (United States). Energy Systems Div.; Kvale, E.P. [Indiana Univ., Bloomington, IN (United States). Indiana Geological Survey

    1995-04-03

    Laminated to thin-bedded siltstones directly overlie Carboniferous coals at several localities in the Eastern Interior Coal Basin. Because lamina thicknesses show cyclical variations, the siltstones have been termed tidal rhythmites. The rhythmites commonly show a repetitive thick-thin pairing of the laminae, and these two-lamina rhythmites have been interpreted as the result of the asymmetry of flood and ebb velocities that affected sedimentation in a diurnal paleotidal system. Alternatively, the pairing has been interpreted to be related to a pronounced difference in height between successive high tides in a semidiurnal system. This explanation suggests deposition in a mixed, predominantly semidiurnal system with a marked diurnal inequality. In addition to the two-lamina rhythmites described originally, subsequent examination of drill cores indicates the occurrence of relatively rare, more complex three- and four-lamina rhythmites. A variety of mathematical techniques are used herein to analyze lamina-thickness data extracted from these rhythmites. Processing techniques include: (1) comparing the linear relationship between the thicknesses of the thinner and thicker laminae and comparing these relationships to modern tidal systems; (2) analyses of thickness periodicities and comparison with modern neap-spring tidal cycles; and (3) extraction of lamina-thickness inequalities and comparison to the diurnal inequalities that occur in semidiurnal tidal systems. These tests indicate that reasonable conclusions can be made for the type of originating paleotidal system. For the cases analyzed herein, the paleotidal signature suggests a mixed, predominantly semidiurnal system with a marked diurnal inequality.

  15. Cycloidal tidal power generation - Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This report summarises the findings of a project investigating the economic and technical viability of a cycloidal tidal stream generator and developing a performance prediction model to assess the applicability of cycloidal turbines to power generation. The concept of cycloidal power generation is described along with the use of the model to examine the performance of six designs in the tidal flow off the west coast of Scotland. Details are given of the estimated power generated and cost reductions using optimised designs. Areas to be examined for design optimisation are listed.

  16. CFD for wind and tidal offshore turbines

    CERN Document Server

    Montlaur, Adeline

    2015-01-01

    The book encompasses novel CFD techniques to compute offshore wind and tidal applications. Computational fluid dynamics (CFD) techniques are regarded as the main design tool to explore the new engineering challenges presented by offshore wind and tidal turbines for energy generation. The difficulty and costs of undertaking experimental tests in offshore environments have increased the interest in the field of CFD which is used to design appropriate turbines and blades, understand fluid flow physical phenomena associated with offshore environments, predict power production or characterise offshore environments, amongst other topics.

  17. Tidal forces in Reissner-Nordstroem spacetimes

    Energy Technology Data Exchange (ETDEWEB)

    Crispino, Luis C.B.; Oliveira, Ednilton S. de [Universidade Federal do Para, Faculdade de Fisica, Belem, Para (Brazil); Higuchi, Atsushi; Oliveira, Leandro A. [University of York, Department of Mathematics, York (United Kingdom)

    2016-03-15

    We analyze the tidal forces produced in the spacetime of Reissner-Nordstroem black holes. We point out that the radial component of the tidal force changes sign just outside the event horizon if the charge-to-mass ratio is close to 1, unlike in Schwarzschild spacetime of uncharged black holes, and that the angular component changes sign between the outer and inner horizons. We solve the geodesic deviation equations for radially falling bodies toward the charged black hole. We find, for example, that the radial component of the geodesic deviation vector starts decreasing inside the event horizon unlike in the Schwarzschild case. (orig.)

  18. Adelie penguin foraging location predicted by tidal regime switching.

    Directory of Open Access Journals (Sweden)

    Matthew J Oliver

    Full Text Available Penguin foraging and breeding success depend on broad-scale environmental and local-scale hydrographic features of their habitat. We investigated the effect of local tidal currents on a population of Adélie penguins on Humble Is., Antarctica. We used satellite-tagged penguins, an autonomous underwater vehicle, and historical tidal records to model of penguin foraging locations over ten seasons. The bearing of tidal currents did not oscillate daily, but rather between diurnal and semidiurnal tidal regimes. Adélie penguins foraging locations changed in response to tidal regime switching, and not to daily tidal patterns. The hydrography and foraging patterns of Adélie penguins during these switching tidal regimes suggest that they are responding to changing prey availability, as they are concentrated and dispersed in nearby Palmer Deep by variable tidal forcing on weekly timescales, providing a link between local currents and the ecology of this predator.

  19. NOAA Historical Tidal Current Data for the Coastal United States

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Knowledge of the timing and strength of tidal currents is extremely important for safe navigation in coastal waters. Tidal currents are almost always the strongest...

  20. NOAA Tidal Current Data for the Coastal United States

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Knowledge of the timing and strength of tidal currents is extremely important for safe navigation in coastal waters. Tidal currents are almost always the strongest...

  1. Analyses of cosmic ray induced-neutron based on spectrometers operated simultaneously at mid-latitude and Antarctica high-altitude stations during quiet solar activity

    Science.gov (United States)

    Hubert, G.

    2016-10-01

    In this paper are described a new neutron spectrometer which operate in the Concordia station (Antarctica, Dome C) since December 2015. This instrument complements a network including neutron spectrometers operating in the Pic-du-Midi and the Pico dos Dias. Thus, this work present an analysis of cosmic ray induced-neutron based on spectrometers operated simultaneously in the Pic-du-Midi and the Concordia stations during a quiet solar activity. The both high station platforms allow for investigating the long period dynamics to analyze the spectral variation and effects of local and seasonal changes, but also the short term dynamics during solar flare events. A first part is devoted to analyze the count rates, the spectrum and the neutron fluxes, implying cross-comparisons between data obtained in the both stations. In a second part, measurements analyses were reinforced by modeling based on simulations of atmospheric cascades according to primary spectra which only depend on the solar modulation potential.

  2. Wind, Wave, and Tidal Energy Without Power Conditioning

    Science.gov (United States)

    Jones, Jack A.

    2013-01-01

    Most present wind, wave, and tidal energy systems require expensive power conditioning systems that reduce overall efficiency. This new design eliminates power conditioning all, or nearly all, of the time. Wind, wave, and tidal energy systems can transmit their energy to pumps that send high-pressure fluid to a central power production area. The central power production area can consist of a series of hydraulic generators. The hydraulic generators can be variable displacement generators such that the RPM, and thus the voltage, remains constant, eliminating the need for further power conditioning. A series of wind blades is attached to a series of radial piston pumps, which pump fluid to a series of axial piston motors attached to generators. As the wind is reduced, the amount of energy is reduced, and the number of active hydraulic generators can be reduced to maintain a nearly constant RPM. If the axial piston motors have variable displacement, an exact RPM can be maintained for all, or nearly all, wind speeds. Analyses have been performed that show over 20% performance improvements with this technique over conventional wind turbines

  3. Assessment of Soil Quality of Tidal Marshes in Shanghai City

    OpenAIRE

    Wang, Qing; TAN, JUAN; SHA, Chenyan; RUAN, Junjie; Min WANG; HUANG, Shenfa; Wu, Jianqiang

    2013-01-01

    We take three types of tidal marshes in Shanghai City as the study object: tidal marshes in mainland, tidal marshes in the rim of islands, and shoal in Yangtze estuary. On the basis of assessing nutrient quality and environmental quality, respectively, we use soil quality index (SQI) to assess the soil quality of tidal flats, meanwhile formulate the quality grading standards, and analyze the current situation and characteristics of it. The results show that except the north of Hangzhou Bay, N...

  4. Ecological consequences of diurnal flooding in tidal freshwater wetlands

    NARCIS (Netherlands)

    Barendregt, A.; Wassen, M.J.

    2010-01-01

    Diurnal flooding can be observed in the upper end of tidal estuaries, where flooding water originating from the river is constantly fresh. Here, the input from the river is confronted with a tidal wave, so that the sand banks, mud flats, low and high marshes and tidal forests are flooded mostly twic

  5. Development of Tidal areas: some principles and issues towards systainability

    NARCIS (Netherlands)

    Sang Hyun, P.; Simm, J.; Ritzema, H.P.

    2009-01-01

    The coastal zone comprises only 3% of the earth's surface, but contains a disproportionately high amount of its assets. Tidal areas include all those coastal areas where the tidal processes are capable of affecting man's activity or of being influenced by man. Tidal areas differ greatly depending on

  6. Subtidal flow division at a shallow tidal junction

    NARCIS (Netherlands)

    Buschman, F.A.; Hoitink, A.J.F.; Vegt, van der M.; Hoekstra, P.

    2010-01-01

    Tides influence distribution of river discharge at tidally affected channel junctions. At the apex of a channel network in an Indonesian delta, observations of flow division suggest that tidally averaged flow division depends on the tidal range. To understand the mechanisms governing the subtidal fl

  7. Tidal freshwater wetlands, the fresh dimension of the estuary

    NARCIS (Netherlands)

    Barendregt, A.

    2016-01-01

    Upstream in the estuary, where the river ends, the tidal energy is still present but the constant input from the river creates permanent fresh water conditions. The physical, chemical and biological conditions differ from the brackish part of the tidal area, but by processes from the tidal wave also

  8. Salmon habitat use, tidal-fluvial estuary - Columbia River Estuary Tidal Habitats

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The goal of the tidal-fluvial estuary study is to determine the estuary's contribution to the spatial structure and life history diversity of Columbia River salmon...

  9. Methane emission from tidal freshwater marshes

    NARCIS (Netherlands)

    Van der Nat, F.J.; Middelburg, J.J.

    2000-01-01

    In two tidal freshwater marshes, methane emission, production and accumulation in the pore-water have been studied. The two sites differ in their dominant vegetation, i.e., reed and bulrush, and in their heights above sea level. The reed site was elevated in relation to the bulrush site and had high

  10. On the superradiance-tidal friction correspondence

    CERN Document Server

    Glampedakis, K; Kennefick, D

    2013-01-01

    Since the work of Hartle in the 1970s, and the subsequent development of the the Membrane Paradigm approach to black hole physics it has been widely accepted that superradiant scattering of gravitational waves bears strong similarities with the phenomenon of ``tidal friction'' (well-known from Newtonian gravity) operating in binary systems of viscous material bodies. In this paper we revisit the superradiance-tidal friction analogy within the context of ultracompact relativistic bodies. We advocate that as long as these bodies have non-zero viscosity they should undergo tidal friction that can be construed as a kind of superradiant scattering from the point of view of the dynamics of an orbiting test-body. In addition we consider the presence of anisotropic matter, which is required for at least some ultracompact bodies, if they are to sustain a radius very close to the gravitational radius. We find that the tidal friction/superradiance output is enhanced with increasing anisotropy and that strongly anisotrop...

  11. Modeling the hydrodynamics in tidal networks

    NARCIS (Netherlands)

    Alebregtse, N.C.

    2016-01-01

    This thesis covers tidal propagation through networks of channels. Such networks are widespread and are often subject to discordant human and natural interests. First, the effect of a secondary channel on the tides in a main channel is explained with the use of an idealized model and the responsible

  12. Tidal evolution of planets around brown dwarfs

    CERN Document Server

    Bolmont, Emeline; Leconte, Jérémy

    2011-01-01

    The tidal evolution of planets orbiting brown dwarfs (BDs) presents an interesting case study because BDs' terrestrial planet forming region is located extremely close-in. In fact, the habitable zones of BDs range from roughly 0.001 to 0.03 AU and for the lowest-mass BDs are located interior to the Roche limit. In contrast with stars, BDs spin up as they age. Thus, the corotation distance moves inward. This has important implications for the tidal evolution of planets around BDs. We used a standard equilibrium tidal model to compute the orbital evolution of a large ensemble of planet-BD systems. We tested the effect of numerous parameters such as the initial semi-major axis and eccentricity, the rotation period of the BD, the masses of both the BD and planet, and the tidal dissipation factors. We find that all planets that form at or beyond the corotation distance and with initial eccentricities smaller than \\sim 0.1 are repelled from the BD. Some planets initially interior to corotation can survive if their ...

  13. An optimal tuning strategy for tidal turbines

    Science.gov (United States)

    Vennell, Ross

    2016-11-01

    Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This `impatient-tuning strategy' results in far lower power output, much higher structural loads and greater environmental impacts due to flow reduction than an existing `patient-tuning strategy' which maximizes the power output averaged over the tidal cycle. This paper presents a `smart patient tuning strategy', which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows that, counterintuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase a turbine's average power output.

  14. 2008 NWFSC Tidal Freshwater Genetics Results

    Energy Technology Data Exchange (ETDEWEB)

    David Teel

    2009-05-01

    Genetic Analysis of Juvenile Chinook Salmon for inclusion in 'Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008. Annual Report to Bonneville Power Administration, Contract DE-AC05-76RL01830.'

  15. Unravelling tidal dissipation in gaseous giant planets

    CERN Document Server

    Guenel, Mathieu; Remus, Françoise

    2014-01-01

    Tidal dissipation in planetary interiors is one of the key physical mechanisms that drive the evolution of star-planet and planet-moon systems. New constraints are now obtained both in the Solar and exoplanetary systems. Tidal dissipation in planets is intrinsically related to their internal structure. In particular, fluid and solid layers behave differently under tidal forcing. Therefore, their respective dissipation reservoirs have to be compared. In this letter, we compute separately the contributions of the potential dense rocky/icy core and the convective fluid envelope of gaseous giant planets, as a function of core size and mass. We then compare the associated dissipation reservoirs, by evaluating the frequency-average of the imaginary part of the Love numbers $k^2_2$ in each region. In the case of Jupiter and Saturn-like planets, we show that the viscoelastic dissipation in the core could dominate the turbulent friction acting on tidal inertial waves in the envelope. However, the fluid dissipation wou...

  16. On the timing of foraging flights by oystercatchers, haematopus ostralegus, on tidal mudflats

    Science.gov (United States)

    Daan, Serge; Koene, Paul

    The tidal movements of flocks of oystercatchers foraging on mudflats at low tide and roosting inland behind a dike at high tide were studied and the effects of day-to-day variations in the time of mudflat exposure by ebb analysed. High mean water levels and short low tides led to reduced intake during low water due to increased bird densities in addition to temporal constraints (Fig. 4). Increased feeding around the roost apparently compensated for some of the reduced intake (Figs 6 ad 7) although accurate intake measurements could be made for foraging on the tidal flats only. It is argued that optimal timing of foraging flights to coincide with exposure of the mussel banks would contribute to exploitation of this tidal food source. The median departure time from the roosts relative to the time of mudflat exposure was early on days when the tide went out late and late when the tide was early (Figs 8 and 9). Daily variations in departure time were predicted by the daily variations in tabulated high water times, but not by variations in mudflat exposure or coverage (Fig. 10). The conclusion is drawn that the birds employ a timing mechanism not directly associated with the tidal water movements. In some pilot experiments in caged oystercatchers, feeding schedules elicitated feeling attempts in anticipation of expected food. The anticipatory patterns were different for fixed and tidally shifting daily food schedules, and moreover differed between the two feeding times per day (Figs 12 and 13). Five possible mechanisms for tidal anticipation are discussed, making use either of unknown exogenous cues, or of—likewise unknown—endogenous timers of hourglass type of rhythmic with circatidal, circalunadian or circadian period. Experimental tests for these possibilities are outlined.

  17. Analysis of Jiangsu Tidal Flats Reclamation from 1974 to 2012 Using Remote Sensing

    Institute of Scientific and Technical Information of China (English)

    赵赛帅; 刘永学; 李满春; 孙超; 周旻曦; 张荷霞

    2015-01-01

    Jiangsu has the most abundant tidal flat resources among China’s coastal provinces. To ease the conflict between the growing population and shrinking usable land and to promote regional sustainable development, large-scale coastal reclamation development activities have been performed in Jiangsu Province since 1949. The present study has integrated multi-source remote sensing images during 1974 to 2012 by using a Multi-point Fast Marching Method (MFMM) to extract the Jiangsu coastal reclamation areas for different time periods. The temporal and spatial patterns of the extent and elevation of the reclamation areas were analysed in order to determine the unused potential for future reclamation. It will provide information necessary to support the development and construction of tidal flats in Jiangsu. Results show that: (1) the reclaimed tidal flats along the Jiangsu coast cover more than 19.86×104 hm2, of which 13.97×104 hm2 is located in Yancheng, 4.84×104 hm2 in Nantong, and 1.05×104 hm2 in Lianyungang; (2) the average elevation of the reclaimed Jiangsu tidal flats has gradually decreased over the last 40 years, while those in Dongtai and Rudong have showed particularly accelerated decrease since the 1990s; and (3) in 2012, very few unused tidal flats two meters above the sea level are left along the Jiangsu coast, and mainly concentrated in Yancheng. As there are still reserving some coastal land resources between 0−2 m, providing us with a potential for future development. All of these findings may be useful for researchers and local authorities for the development and utilization of tidal flat resources in Jiangsu.

  18. Tidal asymmetry in a funnel-shaped estuary with mixed semidiurnal tides

    Science.gov (United States)

    Gong, Wenping; Schuttelaars, Henk; Zhang, Heng

    2016-05-01

    results show that the FDA exhibits a predominant tendency of shorter duration of low water slack, favoring the landward transport of fine sediment. The FVA demonstrates prevailing ebb dominance in the study period, favoring the seaward transport of coarse sediment. This ebb dominance is primarily induced by the interaction among the residual flow and the tidal constituents. The external TDA in the ocean experiences distinct cyclic variations with positive asymmetry when semidiurnal tides dominate and negative asymmetry during the periods when diurnal tides dominate. The funnel shape of the HE is advantageous for the development of positive tidal asymmetry as the semidiurnal tides are more amplified than the diurnal tides. The effect of river flow can enhance the ebb dominance, while the baroclinic effect is more complex. The existence of channel and shoals favors the development of residual pattern with seaward flow (ebb dominance) in the channel and landward flow (flood dominance) at the shoal when the tides are strong (semidiurnal tides dominate) and the residual pattern with landward flow (flood dominance) in the channel and seaward flow (ebb dominance) at the shoal when the baroclinic effect is dominant (diurnal tides dominate).

  19. Thermal Diffusivity and Strength of Tidal Flat Sediments During a Tidal Simulation

    Science.gov (United States)

    2009-01-01

    energetically dynamic regions on earth. Tidal Hats are repositories of terrigenous and biogenous sediments that are shaped by tides, waves and storms and...and energetically dynamic regions on earth. Tidal flats are repositories of terrigenous and biogenous sediments that are shaped by tides, waves and...strength. Finally, sediment bearing capacity and shear strength increased with packing density with the highest shear strength occurring at depth within the

  20. Prospective HyspIRI global observations of tidal wetlands

    Science.gov (United States)

    Kevin Turpie,; Victor Klemas,; Byrd, Kristin B.; Maggi Kelly,; Young-Heon Jo,

    2015-01-01

    Tidal wetlands are highly productive and act as critical habitat for a wide variety of plants, fish, shellfish, and other wildlife. These ecotones between aquatic and terrestrial environments also provide protection from storm damage, run-off filtering, and recharge of aquifers. Many wetlands along coasts have been exposed to stress-inducing alterations globally, including dredge and fill operations, hydrologic modifications, pollutants, impoundments, fragmentation by roads/ditches, and sea level rise. For wetland protection and sensible coastal development, there is a need to monitor these ecosystems at global and regional scales. Recent advances in satellite sensor design and data analysis are providing practical methods for monitoring natural and man-made changes in wetlands. However, available satellite remote sensors have been limited to mapping primarily wetland location and extent. This paper describes how the HyspIRI hyperspectral and thermal infrared sensors can be used to study and map key ecological properties, such as species composition, biomass, hydrology, and evapotranspiration of tidal salt and brackish marshes and mangroves, and perhaps other major wetland types, including freshwater marshes and wooded/shrub wetlands.

  1. The Tidal Origin of the Environment Dependence of Halo Assembly

    CERN Document Server

    Hahn, Oliver; Dekel, Avishai; Carollo, C Marcella

    2008-01-01

    We uncover the origin of the puzzling anti-correlation between the formation epoch of galactic dark-matter haloes and their environment density. This correlation has been revealed from cosmological N-body simulations and it is in conflict with the simple excursion-set model of halo clustering. Using similar simulations, we first quantify the straightforward association of an early formation epoch with a reduced mass growth rate at late times. We then find that the primary driver of suppressed growth, by accretion or mergers, is tidal effects dominated by a neighbouring massive halo. The tidal effects range from a slowdown of the assembly of haloes due to the shear along the large-scale filaments that feed the massive halo to actual mass loss in haloes that pass through the massive halo. Our results suggest that the dependence of formation epoch on environment density is a secondary effect induced by the enhanced density of haloes in filaments near massive haloes where the tides are strong. Our measures of ass...

  2. Constraining neutron star tidal Love numbers with gravitational wave detectors

    CERN Document Server

    Flanagan, Eanna E

    2007-01-01

    We quantify the ability of ground-based gravitational wave detectors to constrain the nuclear equation of state using the early, low frequency portion of the signal of detected neutron star - neutron star (NS-NS) inspirals. In this early adiabatic regime, the influence of a NS's internal structure on the phase of the waveform depends only on a single parameter lambda of the star related to its tidal Love number, namely the ratio of the induced quadrupole moment to the perturbing tidal gravitational field. We restrict attention to gravitational wave frequencies smaller than a cutoff frequency of 400 Hz. In this domain, f-mode frequency dependent corrections to the internal-structure signal are less than 3%, and higher order multipole corrections are less than 5%, for NS models with f-mode frequencies greater than 1 kHz. For an inspiral of two non-spinning 1.4 solar mass NSs at a signal-to-noise ratio of 20, LIGO I (LIGO II) detectors will be able to constrain lambda to lambda < 1.3 (3.3) 10^(37) g cm^2 s^2 ...

  3. Tidal modulation of two-layer hydraulic exchange flows

    Directory of Open Access Journals (Sweden)

    L. M. Frankcombe

    2006-11-01

    Full Text Available Time-dependent, two layer hydraulic exchange flow is studied using an idealised shallow water model. It is found that barotropic time-dependent perturbations, representing tidal forcing, increase the baroclinic exchange flux above the steady hydraulic limit, with flux increasing monotonically with tidal amplitude (measured either by height or flux amplitude over a tidal period. Exchange flux also depends on the non-dimensional tidal period, γ, which was introduced by Helfrich (1995. Resonance complicates the relationship between exchange flux and height amplitude, but, when tidal strength is characterised by flux amplitude, exchange flux is a monotonic function of γ.

  4. Global aspects of elliptical instability in tidally distorted accretion disks

    CERN Document Server

    Ryu, D; Vishniac, E T; Ryu, Dongsu; Goodman, Jeremy; Vishniac, Ethan T

    1995-01-01

    Tidally distorted accretion disks in binary star systems are subject to a local hydrodynamic instability which excites m=1 internal waves. This instability is three dimensional and approximately incompressible. We study the global aspects of this local instability using equations derived under the shearing sheet approximation, where the effects of the azimuthal variation along distorted orbital trajectories are included in source terms which oscillate with local orbital phase. Linear analyses show that the excitation of the instability is essentially local, i.e. insensitive to radial boundary conditions. The region of rapid growth feeds waves into the region of slow or negligible growth, allowing the instability to become global. The global growth rate depends the maximum local growth rate, the size of the rapid growth region, and the local group velocity. We present an empirical expression for the global growth rate. We note that the local nature of the instability allows the excitation of waves with m\

  5. Shear Stress, Turbulence Production and Dissipation in Small Tidal Channels Intersecting a Tidal Flat

    Science.gov (United States)

    Pieterse, A.; Puleo, J. A.; McKenna, T. E.

    2014-12-01

    A 16-day field experiment was conducted in March and April 2013 in a tidal wetland in Kent County, Delaware. The study area was a tidal flat fed by a second-order channel that flows into the Brockonbridge Gut, a small tributary of Delaware Bay. The goal of the field study was to investigate spatio-temporal variability in the hydrodynamics of the tidal flat and the small channels that intersect it, over the period of one spring-neap tidal cycle. The experiment combined remotely-sensed imagery with high-frequency in-situ measurements. A tower with imagers (RGB, NIR, TIR) was deployed to quantify the spatial variations of inundation of the channels, flat and marsh. In-situ sensors that measure flow velocity, sediment concentration and water depth were deployed at six locations on the tidal flat and in the channels. At three locations, a Nortek Vectrino II - profiling velocimeter was deployed that measures a 30 mm velocity profile at 1 mm vertical increments at 100 Hz. These velocity profiles are used to compute turbulent kinetic energy, turbulence dissipation and stress profiles close to the bed. Results show that peak velocities in the channels occur at the beginning and end of ebbing tide, when the water level is below the tidal flat level. At these instances, peaks in turbulence and bed stress also occur. The flow velocity and turbulence peaks are smaller when the water level does not fall below the tidal flat level. On the tidal flat, the flow velocities and turbulence are generally small compared to the intersecting tidal channel. Maximum flow velocities in the channels are around 0.4 m/s, while on the flat maximum velocities are under 0.1 m/s. A comparison is made between turbulence production and dissipation in both the channel and on the tidal flat to determine if advection and diffusion are important in this environment. In addition, the hydrodynamics at several locations in the channel are compared to investigate changes throughout the study area.

  6. Open boundary conditions for tidally and subtidally forced circulation in a limited-area coastal model using the Regional Ocean Modeling System (ROMS)

    Science.gov (United States)

    Liu, Zhiqiang; Gan, Jianping

    2016-08-01

    In limited-area ocean models, open boundary conditions (OBCs) often create dynamic inconsistencies and perform poorly in resolving tidal or subtidal flow when both forces exist. Orlanski-type radiation OBCs are reasonably efficient at treating the subtidally forced flow, and Flather-type OBCs are commonly adapted for the tidally forced flow. However, neither of them performs well when tidal and subtidal forces simultaneously drive the flows. We have developed a novel OBC that integrates the active OBC in Gan and Allen (2005) and a Flather-type OBC. This new OBC accommodates the concurrent Tidal and Subtidal (TST) forcing, and the respective tidal or subtidal forcing, at the open boundary of a limited-area model. This new TST-OBC treats the tidal component with a Flather-type OBC, and it separates subtidal barotropic and baroclinic components into local (forced) and global (unforced) components. Then an unforced Orlanski-type OBC can be applied to the global part. We applied the TST-OBC to all model variables to reduce dynamic inconsistence. Using the Regional Ocean Modeling System, we applied the TST-OBC to the shallow East China Sea shelf where strong tidal and subtidal forces over complex topography govern the circulation. Our numerical experiments and analyses suggest that the TST-OBC was robust for both concurrent tidal-subtidal forcing and solely tidal or subtidal forcing at the open boundary. It reduced spurious energy reflection, and, overall, it performed better than an Orlanski-type or Flather-type OBC in reproducing realistic tidal and subtidal shelf circulation.

  7. The response of subsurface oceans in icy satellites to tidally driven forcing

    Science.gov (United States)

    Chen, E. M.; Glatzmaier, G. A.; Nimmo, F.

    2009-12-01

    Observations from the Galileo and Cassini spacecraft suggest that subsurface global water oceans are likely present on multiple icy satellites of Jupiter and Saturn. However, the dynamics of these oceans, under the influence of a time-varying tidal potential and buoyancy and coriolis forces, have not been investigated in detail. We have investigated the large scale ocean flow in two ways. First, we simulate the 3-D global circulation of the subsurface oceans on Europa and Titan driven primarily by a time-varying tidal potential and secondarily by heating at the base of the ocean. Second, we analyze the behavior of tidally-forced subsurface oceans in two-dimensions using quasi-nonlinear shallow water theory. These approaches allow us to predict potentially observable effects, in particular non-synchronous rotation of the ice shell driven by ocean torques and spatial variations in the heat flow supplied to the base of the ice shell, and magnetic induction effects due to the ocean circulation. Time-series analyses suggest that the ocean responds primarily at the tidal frequency; however, there are responses at lower frequencies as well. Preliminary results of full 3-D simulations will be presented, and comparisons will be made to the forced shallow water model.

  8. XMMSL1J063045.9-603110: a tidal disruption event fallen into the back burner

    Science.gov (United States)

    Mainetti, Deborah; Campana, Sergio; Colpi, Monica

    2016-07-01

    Black holes at the centre of quiescent galaxies can be switched on when they accrete gas that is gained from stellar tidal disruptions. A star approaching a black hole on a low angular momentum orbit may be ripped apart by tidal forces, which triggers raining down of a fraction of stellar debris onto the compact object through an accretion disc and powers a bright flare. In this paper we discuss XMMSL1J063045.9-603110 as a candidate object for a tidal disruption event. The source has recently been detected to be bright in the soft X-rays during an XMM-Newton slew and later showed an X-ray flux decay by a factor of about 10 in twenty days. We analyse XMM-Newton and Swift data. XMMSL1J063045.9-603110 shows several features typical of tidal disruption events: the X-ray spectrum shows the characteristics of a spectrum arising from a thermal accretion disc, the flux decay follows a t-5/3 law, and the flux variation is >350. Optical observations testify that XMMSL1J063045.9-603110 is probably associated with an extremely small galaxy or even a globular cluster, which suggests that intermediate-mass black holes are located in the cores of (at least) some of them.

  9. Electromagnetic inductance plethysmography is well suited to measure tidal breathing in infants

    Science.gov (United States)

    Eriksen, Morten; Olsen, Merete S.; Markestad, Trond; Halvorsen, Thomas

    2016-01-01

    Reliable, accurate and noninvasive methods for measuring lung function in infants are desirable. Electromagnetic inductance plethysmography has been used to perform infant spirometry and VoluSense Pediatrics (VSP) (VoluSense, Bergen, Norway) represents an updated version of this technique. We aimed to examine its accuracy compared to a validated system measuring airflow via a facemask using an ultrasonic flowmeter. We tested 30 infants with postmenstrual ages between 36 to 43 weeks and weights from 2.3 to 4.8 kg, applying both methods simultaneously and applying VSP alone. Agreement between the methods was calculated using Bland–Altman analyses and we also estimated the effect of applying the mask. Mean differences for all breathing parameters were within ±5.5% and limits of agreement between the two methods were acceptable, except perhaps for peak tidal expiratory flow (PTEF). Application of the facemask significantly increased tidal volume, minute ventilation, PTEF, the ratio of inspiratory to expiratory time and the ratio of expiratory flow at 50% of expired volume to PTEF. VSP accurately measured tidal breathing parameters and seems well suited for tidal breathing measurements in infants under treatment with equipment that precludes the use of a facemask. PMID:28053968

  10. XMMSL1J063045.9-603110: a tidal disruption event fallen into the back burner

    CERN Document Server

    Mainetti, Deborah; Colpi, Monica

    2016-01-01

    Black holes at the centre of quiescent galaxies can be switched on when they accrete gas gained from stellar tidal disruptions. A star approaching a black hole on a low angular momentum orbit may be ripped apart by tidal forces, raining a fraction of stellar debris onto the compact object through an accretion disc and powering a bright flare. In this paper we discuss XMMSL1J063045.9-603110 as a candidate object for a tidal disruption event. The source has been recently detected bright in the soft X-rays during an XMM-Newton slew, showing later on an X-ray flux decay by a factor of about 10 in twenty days. We analyse XMM-Newton and Swift data. XMMSL1J063045.9-603110 shows several features typical of tidal disruption events: the X-ray spectrum is consistent to arise from a thermal accretion disc, the flux decay follows a t^-5/3 law and the flux variation is > 350. Optical observations testify that XMMSL1J063045.9-603110 is likely to be associated with an extremely small galaxy or even a globular cluster, sugges...

  11. Tidal satellite perturbations and the Lense-Thirring effect

    CERN Document Server

    Iorio, L; Iorio, Lorenzo; Pavlis, Erricos C.

    2001-01-01

    The tiny general relativistic Lense-Thirring effect can be measured by means of a suitable combination of the orbital residuals of the nodes of LAGEOS and LAGEOS II and the perigee of LAGEOS II. This observable is affected, among other factors, by the Earth' s solid and ocean tides. They induce long-period orbital perturbations that, over observational periods of few years, may alias the detection of the gravitomagnetic secular trend of interest. In this paper we calculate explicitly the most relevant tidal perturbations acting upon LAGEOSs and assess their influence on the detection of the Lense-Thirring effect. The present day level of knowledge of the solid and ocean tides allow us to conclude that their influence on it ranges from almost 4% over 4 years to less than 2% over 7 years.

  12. Power Generation for River and Tidal Generators

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wright, Alan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gevorgian, Vahan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Donegan, James [Ocean Renewable Power Company (ORPC), Portland, ME (United States); Marnagh, Cian [Ocean Renewable Power Company (ORPC), Portland, ME (United States); McEntee, Jarlath [Ocean Renewable Power Company (ORPC), Portland, ME (United States)

    2016-06-01

    Renewable energy sources are the second largest contributor to global electricity production, after fossil fuels. The integration of renewable energy continued to grow in 2014 against a backdrop of increasing global energy consumption and a dramatic decline in oil prices during the second half of the year. As renewable generation has become less expensive during recent decades, and it becomes more accepted by the global population, the focus on renewable generation has expanded from primarily wind and solar to include new types with promising future applications, such as hydropower generation, including river and tidal generation. Today, hydropower is considered one of the most important renewable energy sources. In river and tidal generation, the input resource flow is slower but also steadier than it is in wind or solar generation, yet the level of water turbulent flow may vary from one place to another. This report focuses on hydrokinetic power conversion.

  13. Tidal heating in close binary stellar systems

    Energy Technology Data Exchange (ETDEWEB)

    Rieutord, M.; Bonazzola, S.

    1987-07-15

    Tidal heating of a low-mass star in a close binary system, resulting from the conjugate effect of angular momentum loss and tidal action, is investigated via detailed study of the flow inside the secondary. It is found in the case of cataclysmic binaries that viscous dissipation is at most 10/sup -3/ x the nuclear luminosity of the star. It is shown, however, that the dissipation is very sensitive to the turbulent viscosity in the envelope of the secondary. The case of very close pairs of white dwarfs is also considered. It is shown that such pairs, which are thought to be the progenitors of Type I Supernovae may dissipate a power as large as 10/sup 38/ erg s/sup -1/, provided that they reach synchronization; such a heating will strongly modify the conditions in which the nuclear explosion starts.

  14. Climate instability on tidally locked exoplanets

    CERN Document Server

    Kite, Edwin S; Manga, Michael

    2011-01-01

    Feedbacks that can destabilize the climates of synchronously-rotating rocky planets may arise on planets with strong day-night surface temperature contrasts. Earth-like habitable-zone (HZ) planets maintain stable surface liquid water over geological time. This requires equilibrium between the temperature-dependent rate of greenhouse-gas consumption by weathering,and greenhouse-gas resupply by other processes. Detected small-radius exoplanets, and anticipated M-dwarf HZ rocky planets, are expected to be tidally locked. We investigate two feedbacks that can destabilize climate on tidally-locked planets. (1) If small changes in pressure alter the temperature distribution across a planet's surface such that the weathering rate increases when the pressure decreases, a positive feedback occurs involving increasing weathering rate near the substellar point, decreasing pressure, and increasing substellar surface temperature. (2) When decreases in pressure increase the surface area above the melting point (through red...

  15. Tidal flat erosion of the Huanghe River Delta due to local changes in hydrodynamic conditions

    Institute of Scientific and Technical Information of China (English)

    JIA Yonggang; ZHENG Jiewen; YUE Zhongqi; LIU Xiaolei; SHAN Hongxian

    2014-01-01

    An ideal nature system for the study of post-depositional submarine mass changing under wave loading was selected in the inter-tidal platform of the subaqueous Huanghe River Delta, a delta formed during pe-riod from 1964 to 1976 as the Huanghe River discharged into the Bohai Gulf by Diaokou distributary. A road embankment constructed for petroleum recovery on the inter-tidal platform in 1995 induced the essential varieties of hydrodynamic conditions on the both sides of the road. With both sides sharing similarities in (1) initial sedimentary environment, (2) energetic wave loading, (3) differential hydrodynamic conditions in later stages, (4) enough long-range action, and (5) extreme shallow water inter-tidal platforms;the study is representative and feasible as well. Two study sites were selected on each side of the road, and a series of measurements, samplings, laboratory experiments have been carried out, including morphometry, hydro-dynamic conditions, sediment properties, granularity composition, and fractal dimension calculation of the topography in the two adjacent areas. It was observed that in the outer zone, where wave loading with high magnitude prevailed, the tidal flat was bumpy and exhibited a high erosion rate and high fractal dimension. Further, the fractal dimension diminished quickly, keeping with the enlarging of calculative square size. However in the inner zone, where the hydrodynamic condition was weak, the tidal flat was flat and exhibited a low erosion rate and low fractal dimensions;the fractal dimension diminished with the enlarging of calcu-lative square size. The fractal dimensions in the different hydrodynamic areas equalized increasingly as the calculative square size accreted to threshold, indicating that the hydrodynamic condition plays a significant role in topography construction and submarine delta erosion process. Additionally, the later differentiation of sediment properties, granularity composition, microstructure

  16. DIRECTLY IMAGING TIDALLY POWERED MIGRATING JUPITERS

    Energy Technology Data Exchange (ETDEWEB)

    Dong Subo; Katz, Boaz; Socrates, Aristotle [Institute for Advanced Study, Princeton, NJ 08540 (United States)

    2013-01-10

    Upcoming direct-imaging experiments may detect a new class of long-period, highly luminous, tidally powered extrasolar gas giants. Even though they are hosted by {approx} Gyr-'old' main-sequence stars, they can be as 'hot' as young Jupiters at {approx}100 Myr, the prime targets of direct-imaging surveys. They are on years-long orbits and presently migrating to 'feed' the 'hot Jupiters'. They are expected from 'high-e' migration mechanisms, in which Jupiters are excited to highly eccentric orbits and then shrink semimajor axis by a factor of {approx}10-100 due to tidal dissipation at close periastron passages. The dissipated orbital energy is converted to heat, and if it is deposited deep enough into the atmosphere, the planet likely radiates steadily at luminosity L {approx} 100-1000 L{sub Jup}(2 Multiplication-Sign 10{sup -7}-2 Multiplication-Sign 10{sup -6} L{sub Sun }) during a typical {approx} Gyr migration timescale. Their large orbital separations and expected high planet-to-star flux ratios in IR make them potentially accessible to high-contrast imaging instruments on 10 m class telescopes. {approx}10 such planets are expected to exist around FGK dwarfs within {approx}50 pc. Long-period radial velocity planets are viable candidates, and the highly eccentric planet HD 20782b at maximum angular separation {approx}0.''08 is a promising candidate. Directly imaging these tidally powered Jupiters would enable a direct test of high-e migration mechanisms. Once detected, the luminosity would provide a direct measurement of the migration rate, and together with mass (and possibly radius) estimate, they would serve as a laboratory to study planetary spectral formation and tidal physics.

  17. Tidal Heating in Multilayered Terrestrial Exoplanets

    Science.gov (United States)

    Henning, Wade G.; Hurford, Terry

    2014-01-01

    The internal pattern and overall magnitude of tidal heating for spin-synchronous terrestrial exoplanets from 1 to 2.5 R(sub E) is investigated using a propagator matrix method for a variety of layer structures. Particular attention is paid to ice-silicate hybrid super-Earths, where a significant ice mantle is modeled to rest atop an iron-silicate core, and may or may not contain a liquid water ocean. We find multilayer modeling often increases tidal dissipation relative to a homogeneous model, across multiple orbital periods, due to the ability to include smaller volume low viscosity regions, and the added flexure allowed by liquid layers. Gradations in parameters with depth are explored, such as allowed by the Preliminary Earth Reference Model. For ice-silicate hybrid worlds, dramatically greater dissipation is possible beyond the case of a silicate mantle only, allowing non-negligible tidal activity to extend to greater orbital periods than previously predicted. Surface patterns of tidal heating are found to potentially be useful for distinguishing internal structure. The influence of ice mantle depth and water ocean size and position are shown for a range of forcing frequencies. Rates of orbital circularization are found to be 10-100 times faster than standard predictions for Earth-analog planets when interiors are moderately warmer than the modern Earth, as well as for a diverse range of ice-silicate hybrid super-Earths. Circularization rates are shown to be significantly longer for planets with layers equivalent to an ocean-free modern Earth, as well as for planets with high fractions of either ice or silicate melting.

  18. Interactions Between Wetlands and Tidal Inlets

    Science.gov (United States)

    2008-08-01

    Madre, TX), (3) fjord-type (e.g., Penobscot Bay , ME), and (4) tectonically created estuaries (e.g., San Francisco Bay , CA) (Pritchard 1967). This CHETN...small marsh island in San Francisco Bay , CA. Wolaver et al. (1988) measured suspended sediment flux of 827 g/m2/year into a marsh in North Inlet, SC...permanent or ephemeral inlets. Conversely, the development or construction of wetlands within an estuary reduces bay area and the tidal prism, which will

  19. Tidal effects on the shoreface: Towards a conceptual framework

    Science.gov (United States)

    Dashtgard, Shahin E.; MacEachern, James A.; Frey, Shannon E.; Gingras, Murray K.

    2012-11-01

    Tidal processes can have a significant impact on the sedimentological and ichnological character of wave-dominated shoreface deposits. As the influence of tides increases, the resulting shoreface successions begin to depart markedly from those postulated by the conventional, wave-dominated shoreface model, which was built upon essentially non-tidal shoreline settings. In shoreface settings subject to stronger tidal flux, tides can be manifest either directly or indirectly. Direct tidal effects refer to those characteristics imparted by tidal energy (e.g., tidal currents) per se, and are best expressed in offshore and lower shoreface positions. Key evidence of direct tidal control includes uniform sediment calibres from the upper shoreface to the offshore, and little or no mud preserved in the lower shoreface. Additionally, sands in the lower shoreface and offshore tend to be intensely bioturbated. Where primary stratification is preserved, it largely comprises current-generated structures. Such shoreface deposits are referred to herein as "tide-influenced shorefaces", and are expected in settings with low storm-wave input coupled with strong tidal currents (e.g., straits). Indirect tidal influences are manifest by the lateral translation of wave zones across the shoreface profile owing to changes in water depth during the tidal cycle. This is best developed in macrotidal to megatidal settings. Indirect tidal influences are more pronounced in the upper and lower shoreface, and are recorded through the interbedding of sedimentary structures produced by shoaling waves, breakers and surf, swash-backwash, and surface runoff. The boundaries between shoreface subenvironments are correspondingly poorly defined. The foreshore in settings of elevated tidal range is also generally much thicker (typically 4 to 5 m). Bioturbation tends to be patchy in distribution across the shoreface, and dominated by vertical structures. Such systems are defined as "tidally modulated

  20. The tidal filament of NGC 4660

    CERN Document Server

    Kemp, S N; Marquez-Lugo, R A; Zepeda-Garcia, D; Franco-Hernandez, R; Nigoche-Netro, A; Ramos-Larios, G; Navarro, S G; Corral, L J

    2016-01-01

    NGC 4660, in the Virgo cluster, is a well-studied elliptical galaxy which has a strong disk component (D/T about 0.2-0.3). The central regions including the disk component have stellar populations with ages about 12-13 Gyr from SAURON studies. However we report the discovery of a long narrow tidal filament associated with the galaxy in deep co-added Schmidt plate images and deep CCD frames, implying that the galaxy has undergone a tidal interaction and merger within the last few Gyr. The relative narrowness of the filament implies a wet merger with at least one spiral galaxy involved, but the current state of the system has little evidence for this. However a 2-component photometric fit using GALFIT shows much bluer B-V colours for the disk component than for the elliptical component, which may represent a residual trace of enhanced star formation in the disk caused by the interaction 1-2 Gyr ago. There are brighter concentrations within the filament which resemble Tidal Dwarf Galaxies, although they are at l...

  1. Signatures of LCDM substructure in tidal debris

    CERN Document Server

    Siegal-Gaskins, Jennifer M

    2007-01-01

    In the past decade, surveys of the stellar component of the Galaxy such as SDSS and 2MASS have revealed a number of stellar streams. Current and future observations are rapidly increasing the precision and quantity of data available, raising the possibility of using tidal streams to constrain the distribution of dark matter in the halo. Simulations of hierarchical structure formation in LCDM cosmologies predict that the dark matter halo of a galaxy like the Milky Way contains a smooth component as well as hundreds of subhalos with masses of ~10^8 solar masses and greater, and it has been suggested that the existence of coherent tidal streams is incompatible with the expected abundance of substructure. We investigate the properties of tidal streams arising from the disruption of satellites in a variety of dark matter halo models. In general, we find that the halo shape and the specific orbital path more strongly determine the degree of disruption of the satellite than does the presence or absence of substructu...

  2. Multiband lightcurves of tidal disruption events

    CERN Document Server

    Lodato, Giuseppe

    2010-01-01

    Unambiguous detection of the tidal disruption of a star would allow an assessment of the presence and masses of supermassive black holes in quiescent galaxies. It would also provide invaluable information on bulge scale stellar processes (such as two-body relaxation) via the rate at which stars are injected into the tidal sphere of influence of the black holes. This rate, in turn, is essential to predict gravitational radiation emission by compact object inspirals. The signature of a tidal disruption event is thought to be a fallback rate for the stellar debris onto the black hole that decreases as $t^{-5/3}$. This mass flux is often assumed to yield a luminous signal that decreases in time at the same rate. In this paper, we calculate the monochromatic lightcurves arising from such an accretion event. Differently from previous studies, we adopt a more realistic description of the fallback rate and of the super-Eddigton accretion physics. We also provide simultaneous lightcurves in optical, UV and X-rays. We ...

  3. Tidal evolution of the Moon from a high-obliquity, high-angular-momentum Earth

    Science.gov (United States)

    Ćuk, Matija; Hamilton, Douglas P.; Lock, Simon J.; Stewart, Sarah T.

    2016-11-01

    In the giant-impact hypothesis for lunar origin, the Moon accreted from an equatorial circum-terrestrial disk; however, the current lunar orbital inclination of five degrees requires a subsequent dynamical process that is still unclear. In addition, the giant-impact theory has been challenged by the Moon’s unexpectedly Earth-like isotopic composition. Here we show that tidal dissipation due to lunar obliquity was an important effect during the Moon’s tidal evolution, and the lunar inclination in the past must have been very large, defying theoretical explanations. We present a tidal evolution model starting with the Moon in an equatorial orbit around an initially fast-spinning, high-obliquity Earth, which is a probable outcome of giant impacts. Using numerical modelling, we show that the solar perturbations on the Moon’s orbit naturally induce a large lunar inclination and remove angular momentum from the Earth-Moon system. Our tidal evolution model supports recent high-angular-momentum, giant-impact scenarios to explain the Moon’s isotopic composition and provides a new pathway to reach Earth’s climatically favourable low obliquity.

  4. Tidal reversal and flow velocities using temperature and specific conductance in a small wetland creek

    Science.gov (United States)

    Eaton, Timothy T.

    2016-11-01

    Characterizing flow dynamics in very small tidal creeks is complicated and not well suited to methods developed for upland streams or coastal estuaries, due to low flows, bidirectionality and shallow waters. Simple instrumentation enables thermal and salinity signals to be used to observe flow directions and estimate velocities in these settings. Using multiple inexpensive sensors over 500 m along a tidally influenced wetland creek, I demonstrate how advection of temperature and specific conductance pulses reveal flood and ebb tides and the temporary reversal of flow by warmer, estuarine water from the receiving embayment. The sequential rise of temperature upstream was most evident under hot and dry conditions, after daily peak air temperatures of 25 °C or above, and was subdued or disrupted under cooler or rainy conditions in summertime. Changes in specific conductance at successive sites upstream were less susceptible to environmental influences and confirm tidal flood velocity of between 0.07 and 0.37 m/s. The tidally-induced flow reversal suggests that periodic high tide conditions can interfere with rapid dispersal of pollution discharges, such as from the combined sewer overflow (CSO) located upstream of the studied creek reach. This low-cost approach of temperature and specific conductance sensing in vegetated coastal wetlands where access, precise elevation control and creek discharge measurements are difficult, provides a simple way of tracking water masses when sufficient contrast exists between water sources.

  5. Tidal evolution of the Moon from a high-obliquity, high-angular-momentum Earth.

    Science.gov (United States)

    Ćuk, Matija; Hamilton, Douglas P; Lock, Simon J; Stewart, Sarah T

    2016-11-17

    In the giant-impact hypothesis for lunar origin, the Moon accreted from an equatorial circum-terrestrial disk; however, the current lunar orbital inclination of five degrees requires a subsequent dynamical process that is still unclear. In addition, the giant-impact theory has been challenged by the Moon's unexpectedly Earth-like isotopic composition. Here we show that tidal dissipation due to lunar obliquity was an important effect during the Moon's tidal evolution, and the lunar inclination in the past must have been very large, defying theoretical explanations. We present a tidal evolution model starting with the Moon in an equatorial orbit around an initially fast-spinning, high-obliquity Earth, which is a probable outcome of giant impacts. Using numerical modelling, we show that the solar perturbations on the Moon's orbit naturally induce a large lunar inclination and remove angular momentum from the Earth-Moon system. Our tidal evolution model supports recent high-angular-momentum, giant-impact scenarios to explain the Moon's isotopic composition and provides a new pathway to reach Earth's climatically favourable low obliquity.

  6. Sedimentary history of the eastern Bohai Sea, China since the deglacial and implications for paleo-tidal current

    Science.gov (United States)

    Yao, Zhengquan; Shi, Xuefa

    2016-04-01

    Numerical simulation suggests that the Holocene sediments re-suspension and distribution in the Bohai Sea was mainly controlled by tidal current regime, which was closely related with sea-level change. Study on sediments in the Bohai Sea thus can provide insights into the evolution of tidal-influenced sedimentary environment and its links with sea-level change. Our understanding of this issue remains incomplete, however, owing to the lack of comprehensive study on sediment core with high-resolution proxies to test such inference. In this study, analyses of sedimentary facies, proxies (grain size, total organic carbon and total nitrogen, X-ray fluorescence scanning Sulfur and Chlorine ratio) and accelerator mass spectrometry 14C dates of a sediment core recovered from the eastern Bohai Sea were carried out to clarify the Holocene sedimentary environment, tidal current change and its relation to the sea-level. The results indicate that the eastern Bohai Sea was dominated by fluvial-coastal environment prior to 12400 cal. a BP due to the sea-level lowstand and changed to tidal-influenced environment from 12400 to 6700 cal. a BP following the rapid sea-level rising. Thereafter shelf environment with minor tidal influence dominated the eastern Bohai Sea under the condition of a deceleration of sea-level rise. The significant change at ~6700 cal. a BP both in sedimentary environment and sediment proxies, indicating an environmental transition from strong tidal-influenced to less tidal-influenced setting. With the sea-level rising from the early Holocene to the mid-Holocene, tidal-current was much strong due to the low sea-level stand and became weak after the maximum transgression at ~6700 cal. a BP. These results are consistent with the numerical simulation, which suggested that less strong tidal current were the consequence of the most highstand sea-level since the mid-Holocene. Our study thus provides a sedimentary record to support the interpretation of numerical

  7. Estimating effects of tidal power projects and climate change on threatened and endangered marine species and their food web.

    Science.gov (United States)

    Busch, D Shallin; Greene, Correigh M; Good, Thomas P

    2013-12-01

    Marine hydrokinetic power projects will operate as marine environments change in response to increased atmospheric carbon dioxide concentrations. We considered how tidal power development and stressors resulting from climate change may affect Puget Sound species listed under the U.S. Endangered Species Act (ESA) and their food web. We used risk tables to assess the singular and combined effects of tidal power development and climate change. Tidal power development and climate change posed risks to ESA-listed species, and risk increased with incorporation of the effects of these stressors on predators and prey of ESA-listed species. In contrast, results of a model of strikes on ESA-listed species from turbine blades suggested that few ESA-listed species are likely to be killed by a commercial-scale tidal turbine array. We applied scenarios to a food web model of Puget Sound to explore the effects of tidal power and climate change on ESA-listed species using more quantitative analytical techniques. To simulate development of tidal power, we applied results of the blade strike model. To simulate environmental changes over the next 50 years, we applied scenarios of change in primary production, plankton community structure, dissolved oxygen, ocean acidification, and freshwater flooding events. No effects of tidal power development on ESA-listed species were detected from the food web model output, but the effects of climate change on them and other members of the food web were large. Our analyses exemplify how natural resource managers might assess environmental effects of marine technologies in ways that explicitly incorporate climate change and consider multiple ESA-listed species in the context of their ecological community. Estimación de los Efectos de Proyectos de Energía de las Mareas y el Cambio Climático sobre Especies Marinas Amenazadas y en Peligro y su Red Alimentaria.

  8. A gravito-electromagnetic analogy based on tidal tensors

    CERN Document Server

    Costa, L F; Herdeiro, Carlos A. R.

    2006-01-01

    We propose a new approach to a physical analogy between General Relativity and Electromagnetism, based on comparing tidal tensors of both theories. Using this approach we write a covariant form for the gravitational analogues of the Maxwell equations, from which the regime of validity of the analogy becomes manifest. Two explicit realisations of the analogy are given. The first one matches linearised gravitational tidal tensors to exact electromagnetic tidal tensors in Minkwoski spacetime. The second one matches exact magnetic gravitational tidal tensors for ultra-stationary metrics to exact magnetic tidal tensors of electromagnetism in curved spaces. We then establish a new proof for a class of tensor identities that define invariants of the type $\\vec{E}^2-\\vec{B}^2$ and $\\vec{E}\\cdot\\vec{B}$, and we exhibit the invariants built from tidal tensors in both gravity and electromagnetism. We contrast our approach with the two gravito-electromagnetic analogies commonly found in the literature, which are reviewed...

  9. International tidal gravity reference values at Wuhan station

    Institute of Scientific and Technical Information of China (English)

    许厚泽; 孙和平; 徐建桥; 陶国祥

    2000-01-01

    The international tidal gravity reference values at Wuhan station are determined accurately based on the comprehensive analysis of the tidal gravity observations obtained from 8 instruments. By comparing these with those in the tidal models given by Dehant (1997) while considering simultaneously (i) the global satellite altimeters tidal data, and (ii) the Schwiderski global tidal data and the local ones along the coast of China, it is found that the average discrepancy of the amplitude factors and of the phase differences for four main waves are given as 5.2% and 3.6% and as 0.16?and 0.08?respectively. They are improved evidently compared to those determined in early stage, indicating the important procedures in improving the Wuhan international tidal gravity reference values when including the long-series observations obtained with a superconducting gravimeter, and when considering the influence of the ocean loading and of the nearly daily free wobble of the Earth’s core.

  10. Tidal bending of glaciers: a linear viscoelastic approach

    DEFF Research Database (Denmark)

    Reeh, Niels; Christensen, Erik Lintz; Mayer, Christoph;

    2003-01-01

    In theoretical treatments of tidal bending of floating glaciers, the glacier is usually modelled as an elastic beam with uniform thickness, resting on an elastic foundation. With a few exceptions, values of the elastic (Young's) modulus E of ice derived from tidal deflection records of floating...... glaciers are in the range 0.9-3 GPa. It has therefore been suggested that the elastic-beam model with a single value of E approximate to 1 GPa adequately describes tidal bending of glaciers.In contrast, laboratory experiments with ice give E =93 GPa, i.e. 3-10 times higher than the glacier-derived values....... This suggests that ice creep may have a significant influence on tidal bending of glaciers. Moreover, detailed tidal-deflection and tilt data from Nioghalvfjerdsfjorden glacier, northeast Greenland, cannot be explained by elastic-beam theory. We present a theory of tidal bending of glaciers based on linear...

  11. Organic geochemistry in Pennsylvanian tidally influenced sediments from SW Indiana

    Energy Technology Data Exchange (ETDEWEB)

    Mastalerz, M.; Kvale, E.P.; Stankiewicz, B.A.; Portle, K. [Indiana University, Bloomington, IN (United States). Indiana Geological Survey

    1999-05-01

    Tidal rhythmites are vertically stacked small-scale sedimentary structures that record daily variations in tidal current energy and are known to overlie some low-sulfur coals in the Illinois Basin. Tidal rhythmites from the Pennsylvanian Brazil Formation in Indiana were analyzed sedimentologically, petrographically, and geochemically in order to understand the character and distribution of organic matter preserved in an environment of daily interactions between marine and fresh waters.

  12. EXPERIMENTAL INVESTIGATIONS ON LONGITUDINAL DISPERSION CHARACTERISTICS OF TIDAL RIVERS

    Institute of Scientific and Technical Information of China (English)

    Fan Jing-yu; Wang Dao-zeng; Zhong Bao-chang

    2003-01-01

    The longitudinal dispersion characteristics of tidal rivers are experimentally investigated in a water channel. The longitudinal dispersion features and influential factors on pollutant in various stages of a tidal period in natural rivers are studied, the value ranges and variation trends of the longitudinal dispersion coefficient are obtained by means of concentration measurement. The results can provide important parameters for establishing the water quality mathematical models in tidal rivers.

  13. Investigation the effect of total solar eclipse March 9, 2016 on tidal elevation study cases: Bangka and Belitung islands

    Science.gov (United States)

    Radjawane, I. M.; Simanjuntak, E. M.; Adziima, A. F.; Sofian, I.

    2016-11-01

    Tidal elevation is generating primary by the gravitational forces between earth with moon and solar. Since the sun plays an important role on generating the tidal sea level then the effect of total solar eclipse (TSE) March 9, 2016 on surface water level has been analysed from real time one-minute tide gauge station from Geospatial Information Agency. Two stations was selected to observe the impact of TSE i.e. in coastal of Bangka Island where totally path of TSE was detected and the other is in the coastal Belitung Island, located near to Bangka Island. We compare the observed sea level with the predicted sea level from 9 constituents using Tidal Model Driver (TMD). The result shows that during the TSE in Bangka Island, the observed tidal phase is shifted and observed sea level is higher compare with the prediction one. But in Belitung Island, there is no pattern change of tidal phase and with small increasing sea level compare with the prediction.

  14. Tidal disruption events from supermassive black hole binaries

    Science.gov (United States)

    Coughlin, Eric R.; Armitage, Philip J.; Nixon, Chris; Begelman, Mitchell C.

    2017-03-01

    We investigate the pre-disruption gravitational dynamics and post-disruption hydrodynamics of the tidal disruption of stars by supermassive black hole (SMBH) binaries. We focus on binaries with relatively low mass primaries (106 M⊙), moderate mass ratios, and separations with reasonably long gravitational wave inspiral times (tens of Myr). First, we generate a large ensemble (between 1 and 10 million) of restricted three-body integrations to quantify the statistical properties of tidal disruptions by circular SMBH binaries of initially unbound stars. Compared to the reference case of a disruption by a single SMBH, the binary potential induces a significant variance into the specific energy and angular momentum of the star at the point of disruption. Second, we use Newtonian numerical hydrodynamics to study the detailed evolution of the fallback debris from 120 disruptions randomly selected from the three-body ensemble (excluding only the most deeply penetrating encounters). We find that the overall morphology of the debris is greatly altered by the presence of the second black hole, and the accretion rate histories display a wide range of behaviours, including order of magnitude dips and excesses relative to control simulations that include only one black hole. Complex evolution typically persists for many orbital periods of the binary. We find evidence for power in the accretion curves on time-scales related to the binary orbital period, though there is no exact periodicity. We discuss our results in the context of future wide-field surveys, and comment on the prospects of identifying and characterizing the subset of events occurring in nuclei with binary SMBHs.

  15. Oceanic Tidal Mixing As a Contributor to Milankovitch-scale Climate Change

    Science.gov (United States)

    Munk, Walter; Bills, Bruce

    2004-01-01

    We propose that changes in the magnitude of oceanic tidal mixing on long time scales is an important, but previously unrecognized, contributor to global climate change. it is well known that Earth's orbital and rotational state changes significantly on 10(exp 4)-10(exp 5) year time scales, and that this influences the spatial and temporal pattern of incident radiation. It is widely supposed that climatic variations on these same time scales are, in large part, a response of the ocean-atmosphere-cryosphere system to this radiative forcing. Our proposal is that variations in the luni-solar tidal potential, induced by these same orbital and rotational variations, influences oceanic mixing and thus modulates meridional heat transport, by amounts which are competitive with the radiative forcing. There are some obvious differences between tidal potential and insolation. First is that the Sun and Moon both contribute to tides, whereas the radiation is entirely of solar origin. Second is that the Earth is transparent to gravity but opaque to radiation. Clipping associated with this opacity makes the radiation pattern temporal spectrum rather more complex than the tidal spectrum. A third point is that solar radiation directly delivers energy to Earth's surface whereas tidal mixing will only expedite lateral transport of heat in association with oceanic thermohaline circulation. The diurnal average insolation pattern is best parameterized via a Fourier series in time of year and Legendre polynomials in sine of latitude. Our present focus will be on the annual average terms. The Legendre degree n=0 term describes the global average insolation, and is nearly constant. The degree n=l term describes differences between northern and southern hemispheres, and the annual mean is zero. The degree n=2 term is the main contributor to the equator to pole variations, and varies with obliquity and orbital eccentricity, with the obliquity variation dominating. The lowest order

  16. Spitzer Observations of Tidal Dwarf Galaxies

    CERN Document Server

    Higdon, Sarah J U

    2007-01-01

    We present Spitzer observations of Tidal Dwarf Galaxies (TDGs) in three interacting systems: NGC 5291, Arp105 and Stephan's Quintet. The spectra show bright emission from polyaromatic hydrocarbons (PAHs), nebular lines and warm molecular hydrogen, characteristic of recent episodes of star formation. The PAH emission that falls in the IRAC 8.0 micron band leads to the TDGs having an extremely red IRAC color, with [4.5] - [8.0] > 3. The emission from PAHs is characterized by a model with mainly neutral 100-C PAH atoms.

  17. Modelling Galaxy Merger Timescales and Tidal Destruction

    CERN Document Server

    Simha, Vimal

    2016-01-01

    We present a model for the dynamical evolution of subhaloes based on an approach combining numerical and analytical methods. Our method is based on tracking subhaloes in an N-body simulation up to the last point that it can be resolved, and applying an analytic prescription for its merger timescale that takes dynamical friction and tidal disruption into account. When applied to cosmological N-body simulations with mass resolutions that differ by two orders of magnitude, the technique produces halo occupation distributions that agree to within 3%.

  18. Atmospheric dynamics of tidally synchronized extrasolar planets.

    Science.gov (United States)

    Cho, James Y-K

    2008-12-13

    Tidally synchronized planets present a new opportunity for enriching our understanding of atmospheric dynamics on planets. Subject to an unusual forcing arrangement (steady irradiation on the same side of the planet throughout its orbit), the dynamics on these planets may be unlike that on any of the Solar System planets. Characterizing the flow pattern and temperature distribution on the extrasolar planets is necessary for reliable interpretation of data currently being collected, as well as for guiding future observations. In this paper, several fundamental concepts from atmospheric dynamics, likely to be central for characterization, are discussed. Theoretical issues that need to be addressed in the near future are also highlighted.

  19. Cycloidal tidal power generation - phase 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This report describes the second phase of a study aimed at addressing the technical and economic viability of cycloidal tidal power generation with the objective of examining design optimisation, the building and testing a scale model, and the use of an enhanced model to estimated the overall system economic performance. Details are given of the analytical and physical modelling studies, the use of Computational Fluid Dynamics (CDF) analysis to understand the fluid flow through the cycloidal unit, the optimisation of the turbine blades, and performance predictions.

  20. Photosynthetic and physiological responses of native and exotic tidal woody seedlings to simulated tidal immersion

    Science.gov (United States)

    Wu, Tonggui; Gu, Shenhua; Zhou, Hefeng; Wang, G. Geoff; Cheng, Xiangrong; Yu, Mukui

    2013-12-01

    Hibiscus hamabo, a native tidal woody species, and Myrica cerifera, an exotic tidal woody species, have been widely planted on coastal beaches in subtropical China. However, whether there are differences in physiological response and tolerance to immersion between the two tidal species is still unknown. Our objectives were to evaluate differences in the photosynthetic and physiological responses to tidal immersion for the two species in the context of sea level rise. With increasing immersion, net photosynthesis, stomatal conductance, intercellular CO2 concentration, and light saturation point declined progressively for both species, whereas dark respiration and light compensation point showed the reverse trend. Lower variation was observed in H. hamabo than in M. cerifera for each index in the same treatment. Photosynthetic ability and utilization of light, especially under high light intensity, decreased for both species. Leaf soluble sugar and protein contents, and glycolate oxidase activity first increased and then decreased with increasing of immersion degree, with the higher values observed in the W4 (4 h duration, 15 cm depth) and W6 (6 h duration, 25 cm depth) treatments for H. hamabo, and W2 (2 h duration, 5 cm depth) and W4 treatments for M. cerifera. These findings indicate that H. hamabo has a better ability to keep the reduction of photosynthesis at a minimum through soluble substance regulated osmotic potential and avoiding excess light damage to the photosynthetic system through increased photorespiration, heat dissipation, chlorophyll fluorescence. Our results suggest that H. hamabo is more tolerant to tidal immersion than M. cerifera, and therefore it is better adapted to the anticipated sea level rise in future.

  1. The origin of neap-spring tidal cycles

    Science.gov (United States)

    Kvale, E.P.

    2006-01-01

    The origin of oceanic tides is a basic concept taught in most introductory college-level sedimentology/geology, oceanography, and astronomy courses. Tides are typically explained in the context of the equilibrium tidal theory model. Yet this model does not take into account real tides in many parts of the world. Not only does the equilibrium tidal model fail to explicate amphidromic circulation, it also does not explain diurnal tides in low latitude positions. It likewise fails to explain the existence of tide-dominated areas where neap-spring cycles are synchronized with the 27.32-day orbital cycle of the Moon (tropical month), rather than with the more familiar 29.52-day cycle of lunar phases (synodic month). Both types of neap-spring cycles can be recognized in the rock record. A complete explanation of the origin of tides should include a discussion of dynamic tidal theory. In the dynamic tidal model, tides resulting from the motions of the Moon in its orbit around the Earth and the Earth in its orbit around the Sun are modeled as products of the combined effects of a series of phantom satellites. The movement of each of these satellites, relative to the Earth's equator, creates its own tidal wave that moves around an amphidromic point. Each of these waves is referred to as a tidal constituent. The geometries of the ocean basins determine which of these constituents are amplified. Thus, the tide-raising potential for any locality on Earth can be conceptualized as the result of a series of tidal constituents specific to that region. A better understanding of tidal cycles opens up remarkable opportunities for research on tidal deposits with implications for, among other things, a more complete understanding of the tidal dynamics responsible for sediment transport and deposition, changes in Earth-Moon distance through time, and the possible influences tidal cycles may exert on organisms. ?? 2006 Elsevier B.V. All rights reserved.

  2. Catalog of worldwide tidal bore occurrences and characteristics

    Science.gov (United States)

    Bartsch-Winkler, S.; Lynch, David K.

    1988-01-01

    Documentation of tidal bore phenomena occurring throughout the world aids in defining the typical geographical setting of tidal bores and enables prediction of their occurrence in remote areas. Tidal bores are naturally occurring, tidally generated, solitary, moving water waves up to 6 meters in height that form upstream in estuaries with semidiurnal or nearly semidiurnal tide ranges exceeding 4 meters. Estuarine settings that have tidal bores typically include meandering fluvial systems with shallow gradients. Bores are well defined, having amplitudes greater than wind- or turbulence-caused waves, and may be undular or breaking. Formation of a bore is dependent on depth and velocity of the incoming tide and river outflow. Bores may occur in series (in several channels) or in succession (marking each tidal pulse). Tidal bores propagate up tidal estuaries a greater distance than the width of the estuary and most occur within 100 kilometers upstream of the estuary mouth. Because they are dynamic, bores cause difficulties in some shipping ports and are targets for eradication. Tidal bores are known to occur, or to have occurred in the recent past, in at least 67 localities in 16 countries at all latitudes, including every continent except Antarctica. Parts of Argentina, Canada, Central America, China, Mozambique, Madagascar, Northern Europe, North and South Korea, the United Kingdom, and the U.S.S.R. probably have additional undiscovered or unreported tidal bores. In Turnagain Arm estuary in Alaska, bores cause an abrupt increase in salinity, suspended sediment, surface character, and bottom pressure, a decrease in illumination of the water column, and a change in water temperature. Tidal bores occurring in Turnagain Arm, Alaska, have the

  3. Dissipation in rocky planets for strong tidal forcing

    Science.gov (United States)

    Clausen, N.; Tilgner, A.

    2015-12-01

    Aims: We plan to reproduce a previously published calculation for the tidal dissipation in Io and extend the employed model to investigate the heat transport mechanism in Io and the thickness of Io's asthenosphere. Additionally, we apply this model to an exoplanet and obtain insights into the dependencies of the modified tidal quality factor (Q') on the size of the planet and its orbital eccentricity. Methods: Tidal dissipation depends on the heat transport mechanism. For strong tidal forcing an equilibrium between heat transport by convection and heat production by tidal dissipation can be obtained that determines the tidal dissipation. By this means, we checked whether convection is the dominant heat transport mechanism in Io. The tidal dissipation also depends on the interior model of Io. We considered various asthenosphere thicknesses and determined which of these gives results compatible with observations. We determined the modified tidal quality factors (Q') for Corot 7 b for various orbital parameters, but in a way that tidal forcing is strong. We used convection and melt migration as possible heat transport mechanism. We repeated this for a hypothetical planet with the size and density of Io on the orbit of Corot 7 b. Results: We find that a heat transport dominated by convection in Io is possible, but the grain sizes need to be smaller than 2.2 mm. For larger grain sizes melt migration is the dominant heat transport mechanism. Moreover, Io's asthenosphere needs to be thicker than 100 km. The computation of the modified tidal quality factors (Q') for Corot 7 b and a planet with the size and density of Io on the orbit of Corot 7 b show that Q' is scattered over several orders of magnitude, but a value of 100 for Q' is an acceptable estimate for a rocky planet under strong tidal forcing.

  4. Multiple Imputation for Network Analyses

    NARCIS (Netherlands)

    Krause, Robert; Huisman, Mark; Steglich, Christian; Snijders, Thomas

    2016-01-01

    Missing data on network ties is a fundamental problem for network analyses. The biases induced by missing edge data, even when missing completely at random (MCAR), are widely acknowledged and problematic for network analyses (Kossinets, 2006; Huisman & Steglich, 2008; Huisman, 2009). Although model-

  5. Tidal Debris as a Dark Matter Probe

    CERN Document Server

    Johnston, Kathryn V

    2016-01-01

    Tidal debris streams from galaxy satellites can provide insight into the dark matter distribution in halos. This is because we have more information about stars in a debris structure than about a purely random population of stars: we know that in the past they were all bound to the same dwarf galaxy; and we know that they form a dynamically cold population moving on similar orbits. They also probe a different region of the matter distribution in a galaxy than many other methods of mass determination, as their orbits take them far beyond the typical extent of those for the bulk of stars. Although conclusive results from this information have yet to be obtained, significant progress has been made in developing the methodologies for determining both the global mass distribution of the Milky Way's dark matter halo and the amount of dark matter substructure within it. Methods for measuring the halo shape are divided into "predictive methods," which predict the tidal debris properties from the progenitor satellite'...

  6. Tidal instability in exoplanetary systems evolution

    Directory of Open Access Journals (Sweden)

    Le Gal P.

    2011-02-01

    Full Text Available A new element is proposed to play a role in the evolution of extrasolar planetary systems: the tidal (or elliptical instability. It comes from a parametric resonance and takes place in any rotating fluid whose streamlines are (even slightly elliptically deformed. Based on theoretical, experimental and numerical works, we estimate the growth rate of the instability for hot-jupiter systems, when the rotation period of the star is known. We present the physical process, its application to stars, and preliminary results obtained on a few dozen systems, summarized in the form of a stability diagram. Most of the systems are trapped in the so-called "forbidden zone", where the instability cannot grow. In some systems, the tidal instability is able to grow, at short timescales compared to the system evolution. Implications are discussed in the framework of misaligned transiting systems, as the rotational axis of the star would be unstable in systems where this elliptical instability grows.

  7. Tidal Disruption Events Prefer Unusual Host Galaxies

    CERN Document Server

    French, K Decker; Zabludoff, Ann

    2016-01-01

    Tidal Disruption Events (TDEs) are transient events observed when a star passes close enough to a supermassive black hole to be tidally destroyed. Many TDE candidates have been discovered in host galaxies whose spectra have weak or no line emission yet strong Balmer line absorption, indicating a period of intense star formation that has recently ended. As such, TDE host galaxies fall into the rare class of quiescent Balmer-strong galaxies. Here, we quantify the fraction of galaxies in the Sloan Digital Sky Survey (SDSS) with spectral properties like those of TDE hosts, determining the extent to which TDEs are over-represented in such galaxies. Galaxies whose spectra have Balmer absorption H$\\delta_{\\rm A}$ $-$ $\\sigma$(H$\\delta_{\\rm A}$) $>$ 4 \\AA\\ (where $\\sigma$(H$\\delta_{\\rm A}$) is the error in the Lick H$\\delta_{\\rm A}$ index) and H$\\alpha$ emission EW $$ 1.31 \\AA\\ and H$\\alpha$ EW $80\\times$ enhancement in such hosts and providing an observational link between the $\\gamma$/X-ray-bright and optical/UV-br...

  8. Tidal Friction: Darwin's Theory Re-Visited

    Science.gov (United States)

    Ferraz-Mello, Sylvio

    2009-05-01

    Our knowledge of tidal friction is even today directly founded on Darwin's theory. Many progresses from studies done in the past century deserve mention. To quote just a few, we may mention Love's theory on the elastic response of one body submitted to an external potential and the understanding of the role played by tides in generating heat in synchronous planetary satellites. We may also mention the many applications that leaded to the understanding of the evolution of systems with close-in satellites, the Earth-Moon system in the first place, and those concerning systems formed by close binary stars. However, notwithstanding the existence of some high-order formal theories, the essential of our knowledge is yet nowadays the one established by Darwin and crucial questions on the action of viscosity, for instance, remains unanswered. We still are strongly tied to Darwin's assumption that the tidal waves lag proportionally to frequency or, in some favorable cases (e.g. the Earth), that the lags are constants. We intend to critically review our current understanding of Darwin's theory and some of its limitations.

  9. Directly Imaging Tidally Powered Migrating Jupiters

    CERN Document Server

    Dong, Subo; Socrates, Aristotle

    2012-01-01

    We show that ongoing direct imaging experiments may detect a new class of long-period, highly luminous, tidally powered extrasolar gas giants. Even though they are hosted by Gyr-"old" main-sequence stars, they can be as "hot" as young Jupiters at ~100 Myr, the prime targets of direct imaging surveys. These planets, with years-long orbits, are presently migrating to "feed" the "hot Jupiters" in steady state. Their existence is expected from a class of "high-e" migration mechanisms, in which gas giants are excited to highly eccentric orbits and then shrink their semi-major axis by factor of ~ 10-100 due to tidal dissipation at successive close periastron passages. The dissipated orbital energy is converted to heat, and if it is deposited deep enough into the planet atmosphere, the planet likely radiates steadily at luminosity ~2-3 orders of magnitude larger than that of our Jupiter during a typical Gyr migration time scale. Their large orbital separations and expected high planet-to-star flux ratios in IR make ...

  10. Tidal Dwarf Galaxies and Missing Baryons

    Directory of Open Access Journals (Sweden)

    Frederic Bournaud

    2010-01-01

    Full Text Available Tidal dwarf galaxies form during the interaction, collision, or merger of massive spiral galaxies. They can resemble “normal” dwarf galaxies in terms of mass, size, and become dwarf satellites orbiting around their massive progenitor. They nevertheless keep some signatures from their origin, making them interesting targets for cosmological studies. In particular, they should be free from dark matter from a spheroidal halo. Flat rotation curves and high dynamical masses may then indicate the presence of an unseen component, and constrain the properties of the “missing baryons,” known to exist but not directly observed. The number of dwarf galaxies in the Universe is another cosmological problem for which it is important to ascertain if tidal dwarf galaxies formed frequently at high redshift, when the merger rate was high, and many of them survived until today. In this paper, “dark matter” is used to refer to the nonbaryonic matter, mostly located in large dark halos, that is, CDM in the standard paradigm, and “missing baryons” or “dark baryons” is used to refer to the baryons known to exist but hardly observed at redshift zero, and are a baryonic dark component that is additional to “dark matter”.

  11. Tidal obliquity evolution of potentially habitable planets

    CERN Document Server

    Heller, René; Barnes, Rory

    2011-01-01

    Stellar insolation has been used as the main constraint on a planet's habitability. However, as more Earth-like planets are discovered around low-mass stars (LMSs), a re-examination of the role of tides on the habitability of exoplanets has begun. Those studies have yet to consider the misalignment between a planet's rotational axis and the orbital plane normal, i.e. the planetary obliquity. We apply two equilibrium tide theories to compute the obliquity evolution of terrestrial planets orbiting in the habitable zones around LMSs. The time for the obliquity to decrease from an Earth-like obliquity of 23.5 deg to 5 deg, the 'tilt erosion time', is compared to the traditional insolation habitable zone (IHZ) as a function of semi-major axis, eccentricity, and stellar mass. We also compute tidal heating and equilibrium rotation caused by obliquity tides. The Super-Earth Gl581d and the planet candidate Gl581g are studied as examples for tidal processes. Earth-like obliquities of terrestrial planets in the IHZ arou...

  12. Effects of serum of the rats ventilated with high tidal volume on endothelial cell permeability and therapeutic effects of ulinastatin

    Institute of Scientific and Technical Information of China (English)

    HUO Guo-dong; CAI Shao-xi; CHEN Bo; CHEN Ying-hua

    2006-01-01

    Background With the widespread use of ventilators in treating critically ill patients, the morbidity of ventilator-induced lung injury (VILI) is increasing accordingly. VILI is characterized by a considerable increase in microvascular leakiness and activation of inflammatory processes. In this study we investigated the effects of inflammatory mediators in VILI rat serum on endothelial cytoskeleton and monolayer cellular permeability, as well as the therapeutic effect of ulinastatin, to explore the pathogenesis and the relationship between biotrauma and lung oedema induced by VILI.Methods Thirty healthy male Sprague-Dawley rats were randomly divided into three groups: group A (normal tidal volume ventilation), group B (high tidal volume ventilation) and group C (high tidal volume ventilation plus ulinastatin). The serum of each rat after ventilation was added to endothelial cell line ECV-304 medium for two hours to observe the effects of serum and/or ulinastatin on endothelial fibrous actin and permeability. Results Compared to rats ventilated with normal tidal volume, serum of rats ventilated with high tidal volume caused a striking reorganization of actin cytoskeleton with a weakening of fluorescent intensity at the peripheral filament bands and formation of the long and thick stress fibres in the centre resulting in endothelial contraction and higher permeability. Prior treatment with ulinastatin lessened the above changes significantly. The changes of permeability coefficient of endothelial permeability after group A, B or C rats serum stimulation were (6.95 ±1.66)%, (27.50±7.77)% and (17.71±4.66)% respectively with statistically significant differences (P<0.05)among the three groups.Conclusions The proinflammatory mediators in the serum of the rats given high tidal volume ventilation increases endothelial permeability by reorganizing actin cytoskeleton, and pretreatment with ulinastatin lessens the permeability by inhibiting of proinflammatory mediators.

  13. Constraints on Tidal Heating in Enceladus

    Science.gov (United States)

    Stevenson, D. J.

    2008-12-01

    Two constraints for Enceladus seem difficult to dispute: First, that it is emitting more heat than allowed by equilibrium tidal heating models (defined as those in which the tidal heat production and orbital eccentricity are constant with time, cf. Meyer and Wisdom, 2007). Second, the maximum possible instantaneous tidal heat generation is over two orders of magnitude larger than what is observed. (This can be shown independent of any particular rheological model.) There is nothing mysterious about the simultaneous correctness of these two statements since one pertains to the orbital evolution aspect of the problem and the other pertains to the actual mechanism of dissipation. In reality, the maximum heat dissipation would never be approached since it would quench the eccentricity in a short timescale (ten to a hundred thousand years). However, this high upper bound assures us that there is no fundamental difficulty with the tidal heating mechanism, only with its constancy over long periods of time. This suggests that one should seek a model in which the eccentricity fluctuates, possibly mediated by the bounds imposed at the high end by the stress limits for ice fracture and at the low end by the stress at which motion on faults (lubricated or dry) ceases to be possible. I will describe models of this kind that are capable, at least in principle, of producing the desired heat flow in instantaneous equilibrium (i.e., without the need to store heat in the interior). This is a stress-mediated model rather than a thermally mediated model (like that advocated for Io, which has a similar disequilibrium problem). Such a model must (in analogy with successful models for Io and Europa) simultaneously provide the right environment for the desired straining of the outer part of the ice shell and a deeper environment that is sufficiently deformable so that a large tidal Love number (of order a hundred times the elastic value) can be achieved. It is argued that solid water ice

  14. The time evolution of gaps in tidal streams

    CERN Document Server

    Helmi, Amina

    2016-01-01

    We model the time evolution of gaps in tidal streams caused by the impact of a dark matter subhalo, while both orbit a spherical gravitational potential. To this end, we make use of the simple behaviour of orbits in action-angle space. A gap effectively results from the divergence of two nearby orbits whose initial phase-space separation is, for very cold thin streams, largely given by the impulse induced by the subhalo. We find that in a spherical potential the size of a gap increases linearly with time, while its density decreases as 1/t^2 for sufficiently long timescales. We have derived an analytic expression that shows how the growth rate depends on the mass of the perturbing subhalo, its scale and its relative velocity with respect to the stream. We have verified these scalings using N-body simulations and find excellent agreement. For example, a subhalo of mass 10^8 Msun directly impacting a very cold thin stream on an inclined orbit can induce a gap that may reach a size of several tens of kpc after a...

  15. Hydrodynamics and morphodynamics of a seasonally forced tidal inlet system

    NARCIS (Netherlands)

    Lam, N.T.; Stive, M.J.F.; Wang, Z.B.; Verhagen, H.J.; Thuy, V.T.T.

    2008-01-01

    Hydrodynamics and morphodynamics of a seasonally forced tidal inlet system are investigated using numerical models. The ocean forcing including tidal and wave actions and sediment transport is simulated using Delft3D model. Fluvial processes in Delft3D are taken into account as results from SOBEK RU

  16. Soil and water management strategies for tidal lowlands in Indonesia

    NARCIS (Netherlands)

    Suryadi, F.X.

    1996-01-01

    Lowland is defined as an area which is relatively low in relation to surface or groundwater levels. Tidal lowlands are lowland areas which are influenced by the vertical tides and their characteristics are in accordance with thier hydro-topographical conditions. Tidal lowlands become more and more i

  17. Land use in Korean tidal wetlands: impacts and management strategies.

    Science.gov (United States)

    Hong, Sun-Kee; Koh, Chul-Hwan; Harris, Richard R; Kim, Jae-Eun; Lee, Jeom-Sook; Ihm, Byung-Sun

    2010-05-01

    The coastal landscapes in southwestern Korea include a diverse array of tidal wetlands and salt marshes. These coastal zones link the ecological functions of marine tidal wetlands and freshwater ecosystems with terrestrial ecosystems. They are rich in biological diversity and play important roles in sustaining ecological health and processing environmental pollutants. Korean tidal wetlands are particularly important as nurseries for economically important fishes and habitats for migratory birds. Diking, draining, tourism, and conversion to agricultural and urban uses have adversely affected Korean tidal wetlands. Recent large development projects have contributed to further losses. Environmental impact assessments conducted for projects affecting tidal wetlands and their surrounding landscapes should be customized for application to these special settings. Adequate environmental impact assessments will include classification of hydrogeomorphic units and consideration of their responses to biological and environmental stressors. As is true worldwide, Korean laws and regulations are changing to be more favorable to the conservation and protection of tidal wetlands. More public education needs to be done at the local level to build support for tidal wetland conservation. Some key public education points include the role of tidal wetlands in maintaining healthy fish populations and reducing impacts of nonpoint source pollution. There is also a need to develop procedures for integrating economic and environmental objectives within the overall context of sustainable management and land uses.

  18. Carbon dioxide uptake by a temperate tidal sea

    NARCIS (Netherlands)

    Klaassen, Wim

    2007-01-01

    Carbon dioxide (CO2) exchange between the atmosphere and the Wadden Sea, a shallow coastal region along the northern Netherlands, has been measured from April 2006 onwards on a tidal flat and over open water. Tidal flat measurements were done using a flux chamber, and ship borne measurements using a

  19. Optical discovery of probable stellar tidal discruption flares

    NARCIS (Netherlands)

    van Velzen, S.; Farrar, G.R.; Gezari, S.; Morrell, N.; Zaritsky, D.; Ostman, L.; Smith, M.; Gelfand, J.; Drake, A.J.

    2012-01-01

    Using archival Sloan Digital Sky Survey (SDSS) multi-epoch imaging data (Stripe 82), we have searched for the tidal disruption of stars by supermassive black holes in non-active galaxies. Two candidate tidal disruption events (TDEs) are identified. The TDE flares have optical blackbody temperatures

  20. Are Wave and Tidal Energy Plants New Green Technologies?

    Science.gov (United States)

    Douziech, Mélanie; Hellweg, Stefanie; Verones, Francesca

    2016-07-19

    Wave and tidal energy plants are upcoming, potentially green technologies. This study aims at quantifying their various potential environmental impacts. Three tidal stream devices, one tidal range plant and one wave energy harnessing device are analyzed over their entire life cycles, using the ReCiPe 2008 methodology at midpoint level. The impacts of the tidal range plant were on average 1.6 times higher than the ones of hydro-power plants (without considering natural land transformation). A similar ratio was found when comparing the results of the three tidal stream devices to offshore wind power plants (without considering water depletion). The wave energy harnessing device had on average 3.5 times higher impacts than offshore wind power. On the contrary, the considered plants have on average 8 (wave energy) to 20 (tidal stream), or even 115 times (tidal range) lower impact than electricity generated from coal power. Further, testing the sensitivity of the results highlighted the advantage of long lifetimes and small material requirements. Overall, this study supports the potential of wave and tidal energy plants as alternative green technologies. However, potential unknown effects, such as the impact of turbulence or noise on marine ecosystems, should be further explored in future research.

  1. 33 CFR 117.181 - Oakland Inner Harbor Tidal Canal.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Oakland Inner Harbor Tidal Canal. 117.181 Section 117.181 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements California § 117.181 Oakland Inner Harbor Tidal Canal. The draws of the...

  2. Morphodynamics of tidal inlets in a tropical monsoon area

    NARCIS (Netherlands)

    Lam, N.T.; Stive, M.J.F.; Verhagen, H.J.; Wang, Z.B.

    2007-01-01

    Morphodynamics of a tidal inlet system on a micro-tidal coast in a tropical monsoon influenced region is modelled and discussed. Influences of river flow and wave climate on the inlet morphology are investigated with the aid of process-based state-of-the-art numerical models. Seasonal and episodic b

  3. Land Use in Korean Tidal Wetlands: Impacts and Management Strategies

    Science.gov (United States)

    Hong, Sun-Kee; Koh, Chul-Hwan; Harris, Richard R.; Kim, Jae-Eun; Lee, Jeom-Sook; Ihm, Byung-Sun

    2010-05-01

    The coastal landscapes in southwestern Korea include a diverse array of tidal wetlands and salt marshes. These coastal zones link the ecological functions of marine tidal wetlands and freshwater ecosystems with terrestrial ecosystems. They are rich in biological diversity and play important roles in sustaining ecological health and processing environmental pollutants. Korean tidal wetlands are particularly important as nurseries for economically important fishes and habitats for migratory birds. Diking, draining, tourism, and conversion to agricultural and urban uses have adversely affected Korean tidal wetlands. Recent large development projects have contributed to further losses. Environmental impact assessments conducted for projects affecting tidal wetlands and their surrounding landscapes should be customized for application to these special settings. Adequate environmental impact assessments will include classification of hydrogeomorphic units and consideration of their responses to biological and environmental stressors. As is true worldwide, Korean laws and regulations are changing to be more favorable to the conservation and protection of tidal wetlands. More public education needs to be done at the local level to build support for tidal wetland conservation. Some key public education points include the role of tidal wetlands in maintaining healthy fish populations and reducing impacts of nonpoint source pollution. There is also a need to develop procedures for integrating economic and environmental objectives within the overall context of sustainable management and land uses.

  4. Flow and sediment transport in an Indonesian tidal network

    NARCIS (Netherlands)

    Buschman, F.A.

    2011-01-01

    The Berau river, situated in east Kalimantan (Indonesia), drains a relatively small catchment area and splits into several interconnected tidal channels. This tidal network connects to the sea. The sea is host to extremely diverse coral reef communities. Also the land side of the region is relativel

  5. Ice-volcanism due to tidal stress on Europa

    Institute of Scientific and Technical Information of China (English)

    LI Li; CHEN Chuxin

    2003-01-01

    Tectonism would be driven by tidal heat on Europa, and there may be ice-volcano on the surface of active Europa. We assume that ice-volcano would spurt out due to tidal stress, and calculate the velocity and height of the spurt inscale. We also find out the approximate distribution of the active volcanoes on Europa.

  6. Residual circulation and tidal stress in the Gulf of California

    Science.gov (United States)

    Salas-De-León, David Alberto; Carbajal-PéRez, Noel; Monreal-Gómez, Maria Adela; Barrientos-MacGregor, Gerardo

    2003-10-01

    Results of a three-dimensional nonlinear barotropic shelf model are used to study the effect of the M2 tidal stress on the residual current in the Gulf of California. The tidal stress summarizes the nonlinear interactions and forces the residual circulation. It is calculated following the method developed by [1975]. The vertical structure of the tidal stress reveals clearly the zones where the interaction between tidal currents and the basin geometry is strong. The highest values of tidal stress were found over the Salsipuedes sill and in the Ballenas Channel in the central archipelago and in the Colorado River Delta. Relatively high values of tidal stress were also found in deeper layers in the southern part. The high tidal stress values coincide well with the anomalous cold-water patches observed in the archipelago area, attributed to tidal mixing. The calculated residual currents show a maximum of about 15 cm s-1 in the upper layers in the archipelago area. At subsurface layers an anticyclonic circulation is observed. Divergence patterns in the upper layers suggest that M2 tide residuals contribute, to significant upward movements of water, on the west side of Tiburón island. This barotropic process may contribute to the generation of the observed cold patches.

  7. Hydromorphology of tidal flats: interactions between hydrodynamics, sediment transport, vegetation and morphology (Invited)

    Science.gov (United States)

    Le Hir, P.; Verney, R.; Bassoullet, P.; Cayocca, F.

    2010-12-01

    Hydrodynamics of tidal flats are first summarised, as resulting from morphology and tidal forcing. Two contrasted configurations are considered: the case where tidal flat is somehow closed and dominant currents are cross-shore, and the case where the flat is opened to a channel system (for instance in estuaries) where long-shore flow is dominant. Maximum tidal currents are discussed, using literature results (e.g. Friedrichs and Aubrey, 1996). Typical convex profiles of tidal dominated systems can be justified: the slope reduction in the upper flat induces a flow acceleration that compensates the flow decay predicted by Friedrichs and Aubrey (1996). Tidal asymmetries and their consequences on sediment transport are also discussed. The importance of wind-induced currents in very shallow waters is illustrated by field measurements (Baie du Mont St-Michel, Seine estuary) and computations. Last, a simple model of cross-shore wave propagation is presented, showing that bottom friction is likely to induce the saturation of wave heights (maximum ratio of wave height over water depth), whatever the offshore wave regime (Le Hir et al., 2000). Dealing with sediment transport, the bottom shear stress distribution is suggested as the relevant parameter for comparing tidal and wave effects. This is confirmed by process-based sediment transport models. Using morphological models that compute erosion, advection and deposition of fine sediments under currents and wave forcing, realistic cross-shore profiles can be simulated (Roberts et al., 2000; Waeles et al., 2004). Starting from any initial condition, the profile converges towards equilibrium, coherently with uniform stress distribution. Depending on the wave forcing, larger slopes appear, generating concave profiles near the low and high water levels, where waves duration is higher (Waeles et al., 2004). The shore profile also depends on the sediment characteristics (settling velocity and shear strength). Similarly, biota are

  8. A new high resolution tidal model in the arctic ocean

    DEFF Research Database (Denmark)

    Cancet, M.; Andersen, Ole Baltazar; Lyard, F.

    The Arctic Ocean is a challenging region for tidal modeling, because of its complex and not well-documented bathymetry, together combined with the intermittent presence of sea ice and the fact that the in situ tidal observations are rather scarce at such high latitudes. As a consequence......-growing maritime and industrial activities in this region. NOVELTIS and DTU Space have developed a regional, high-resolution tidal atlas in the Arctic Ocean, in the framework of the CryoSat Plus for Ocean (CP4O) ESA project. In particular, this atlas benefits from the assimilation of the most complete satellite...... for assimilation and validation. This paper presents the performances of this new regional tidal model in the Arctic Ocean, compared to the existing global tidal models....

  9. Confusion around the tidal force and the centrifugal force

    CERN Document Server

    Matsuda, Takuya; Boffin, Henri M J

    2015-01-01

    We discuss the tidal force, whose notion is sometimes misunderstood in the public domain literature. We discuss the tidal force exerted by a secondary point mass on an extended primary body such as the Earth. The tidal force arises because the gravitational force exerted on the extended body by the secondary mass is not uniform across the primary. In the derivation of the tidal force, the non-uniformity of the gravity is essential, and inertial forces such as the centrifugal force are not needed. Nevertheless, it is often asserted that the tidal force can be explained by the centrifugal force. If we literally take into account the centrifugal force, it would mislead us. We therefore also discuss the proper treatment of the centrifugal force.

  10. Admiralty Inlet Pilot Tidal Project Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Collar, Craig [Public Utility District No. 1 of Snohomish County, Everett, WA (United States)

    2015-09-14

    This document represents the final report for the Admiralty Inlet Pilot Tidal Project, located in Puget Sound, Washington, United States. The Project purpose was to license, permit, and install a grid-connected deep-water tidal turbine array (two turbines) to be used as a platform to gather operational and environmental data on tidal energy generation. The data could then be used to better inform the viability of commercial tidal energy generation from technical, economic, social, and environmental standpoints. This data would serve as a critical step towards the responsible advancement of commercial scale tidal energy in the United States and around the world. In late 2014, Project activities were discontinued due to escalating costs, and the DOE award was terminated in early 2015. Permitting, licensing, and engineering design activities were completed under this award. Final design, deployment, operation, and monitoring were not completed. This report discusses the results and accomplishments achieved under the subject award.

  11. Anelastic tidal dissipation in multi-layer planets

    CERN Document Server

    Remus, F; Zahn, J -P; Lainey, V

    2012-01-01

    Earth-like planets have viscoelastic mantles, whereas giant planets may have viscoelastic cores. The tidal dissipation of such solid regions, gravitationally perturbed by a companion body, highly depends on their rheology and on the tidal frequency. Therefore, modelling tidal interactions presents a high interest to provide constraints on planets' properties and to understand their history and their evolution, in our Solar System or in exoplanetary systems. We examine the equilibrium tide in the anelastic parts of a planet whatever the rheology, taking into account the presence of a fluid envelope of constant density. We show how to obtain the different Love numbers that describe its tidal deformation. Thus, we discuss how the tidal dissipation in solid parts depends on the planet's internal structure and rheology. Finally, we show how the results may be implemented to describe the dynamical evolution of planetary systems. The first manifestation of the tide is to distort the shape of the planet adiabatically...

  12. The interaction of tidal advection, diffusion and mussel filtration in a tidal channel

    Science.gov (United States)

    Simpson, John H.; Berx, Barbara; Gascoigne, Joanna; Saurel, Camille

    2007-12-01

    Time series measurements of flow and pigment concentrations (Chl) in the Menai Strait have revealed that the strong residual flow in a tidal channel (˜ 500 m 3 s - 1 ) transports phytoplankton from the open sea into the channel where much of it is consumed by suspension feeders, mainly in commercial beds of Mytilus edulis. The progressive depletion of phytoplankton along the channel results in a strong horizontal gradient of plankton and hence Chl. Tidal displacement of this gradient causes large (± 50% of mean) oscillations of Chl in the vicinity of the mussel beds. Vertical mixing by the strong tidal flows is sufficiently vigorous for most of the tidal cycle to ensure that downward diffusion can resupply the near-bed layer although there are indications of some transient depletion around slack water. This paradigm of the interaction of advection, diffusion and filtration determining the distribution of plankton and its supply to mussels has been encapsulated in a series of simple models forced only by boundary values. In the first, a 1-D model of tidal flow in the channel reproduces the principal features of the observed currents including the unusually large spatial change in phase of the currents and the variation of the residual transport with tidal range. The flow field from this physical model is used to drive a second model based on the advection diffusion equation for Chl with a source at the Irish Sea boundary and a sink over the mussel bed. This model illustrates the formation of a strong Chl gradient along the channel and simulates the amplitude and phase of the M 2 oscillations of Chl and the development of the M 4 variation apparent in the observations. This second model has been extended to 2-D over the mussel beds to allow investigation of the effects of water column mixing. The model indicates that only for a short period (˜ 30 min), close to slack water, is mixing sufficiently reduced to permit the development of a depletion boundary layer and

  13. Three-dimensional semi-idealized model for tidal motion in tidal estuaries: an application to the Ems estuary

    NARCIS (Netherlands)

    Kumar, Mohit; Schuttelaars, H.M.; Roos, P.C.; Möller, M.

    2016-01-01

    In this paper, a three-dimensional semi-idealized model for tidal motion in a tidal estuary of arbitrary shape and bathymetry is presented. This model aims at bridging the gap between idealized and complex models. The vertical profiles of the velocities are obtained analytically in terms of the firs

  14. Effect of tidal stream power generation on the region-wide circulation in a shallow sea

    Directory of Open Access Journals (Sweden)

    G. I. Shapiro

    2010-10-01

    Full Text Available Ocean tides are deemed to become a stable source of renewable energy for the future. Tidal energy has two components, the first is the potential energy due to sea level variations and the second comes from the kinetic energy of the tidal streams. This paper is concerned with the backward effect on the ocean currents by a tidal stream farm located in the open shallow sea. Recent studies in channels with 1-D models have indicated that the power potential is not given purely by the flux of kinetic energy, as has been commonly assumed. In this study, a 3-D ocean circulation model is used to estimate (i maximum extractable energy at different levels of rated generation capacity of the farm, (ii changes in the strength of currents due to energy extraction, and (iii alterations in the pattern of residual currents and pathways of passive tracers. As water flow is influenced both by tidal and non-tidal currents, the model takes into account wind-driven and density-driven currents generated by meteorological forcing. Numerical modelling has been carried out for a hypothetical circular farm located in the Celtic Sea north of Cornwall, an area known for its high level of tidal energy. Modelling results clearly indicate that extracted power does not grow linearly with the increase in the rated capacity of the farm. For the case studies covered in this paper, a 100-fold increase in rated generation capacity of the farm results only in 7-fold increase in extracted power, this loss of efficiency is much greater than was estimated earlier with 1-D models. In case of high rated capacity of the farm, kinetic energy of currents is altered significantly as far as 10–20 km away from the farm. At high levels of extracted energy the currents tend to avoid flowing through the farm, an effect which is not captured with 1-D models. Residual currents are altered as far as a hundred kilometres. The magnitude of changes in the dispersion of tracers is highly sensitive to

  15. Interior Structure and Tidal Response of Mercury

    Science.gov (United States)

    Steinke, Teresa; Sohl, Frank; Hussmann, Hauke; Knapmeyer, Martin; Wagner, Frank Walter

    2013-04-01

    Recent determinations of Mercury's mean density, polar moment of inertia factor, and the inertia of its solid outer shell provide strong constraints on the radius of its liquid core. We present an ensemble of spherically symmetric interior structure models that all satisfy the observational constraints. The models consist of a pure iron solid inner core, a liquid Fe-FeS outer core, a peridotite mantle and a crust predominantly composed of plagioclase. The sulfur content in the outer core, the iron and magnesium content of the mantle, and the crustal thickness vary throughout the ensemble. Comparison of observed and predicted moments of inertia yields admissible ranges for the outer core radius and the mantle density. From this model ensemble we derive geophysical observables that would allow further constraining the interior structure of Mercury in future experiments. The moment of inertia constraints allow for both forsterite and fayalite rich mantle compositions. Variations of mantle density trade off with crustal thickness and core composition. This non-uniqueness could be resolved using seismic travel time observations: since the P wave velocity of a fayalite mantle is significantly lower than that of the plagioclase-rich crust, a shadow zone arises as a clear discriminant between the two end-member compositions. The planet's response to solar tidal forcing strongly depends on its interior structure and rheological properties and can be parameterized in terms of the surface body tide Love numbers k2 and h2, respectively. We employ the frequency-dependent Maxwell rheology to calculate the body tide Love numbers for the main tidal period (87.97 days) using the density, rigidity and viscosity profiles of our structural models. We obtain values between 0.38 and 0.65 for k2 and between 0.70 and 1.12 for h2, respectively, thereby indicating the substantial tidal response of Mercury's interior. Furthermore we find that, via viscosity and rigidity, both k2 and h2 are

  16. Tidal Interaction as the origin of early-type dwarf galaxies in group environment

    CERN Document Server

    Paudel, Sanjaya

    2014-01-01

    We present a sample of dwarf galaxies that suffer ongoing disruption by the tidal force of nearby massive galaxies. Analysing structural and stellar population properties using the archival imaging and spectroscopic data from the Sloan Digital Sky Survey (SDSS), we find that they are likely a `smoking gun' example of the formation of early-type dwarf galaxies (dEs) in the galaxy group environment through the tidal stirring. Inner cores of these galaxies are fairly intact and the observed light profiles are well fitted with the Sersic functions, while the tidally stretched stellar halos are prominent in the outer parts. They are all located within the 50 kpc sky-projected distance from the center of host galaxies and no dwarf galaxies have relative line-of-sight velocity larger than 205 km/s to their hosts. We derive the Composite Stellar Population (CSP) properties these galaxies by fitting the SDSS optical spectra to a multiple-burst composite stellar population model. We find that these galaxies accumulate ...

  17. Origins and Interpretation of Tidal Debris

    CERN Document Server

    Johnston, Kathryn V

    2016-01-01

    The stellar debris structures that have been discovered around the Milky Way and other galaxies are thought to be formed from the disruption of satellite stellar systems --- dwarf galaxies or globular clusters --- by galactic tidal fields. The total stellar mass in these structures is typically tiny compared to the galaxy around which they are found, and it is hence easy to dismiss them as inconsequential. However, they are remarkably useful as probes of a galaxy's history (as described in this chapter) and mass distribution (covered in a companion chapter in this volume). This power is actually a consequence of their apparent insignificance: their low contribution to the overall mass makes the physics that describes them both elegant and simple and this means that their observed properties are relatively easy to understand and interpret.

  18. Secular and tidal evolution of circumbinary systems

    CERN Document Server

    Correia, Alexandre C M; Laskar, Jacques

    2016-01-01

    We investigate the secular dynamics of three-body circumbinary systems under the effect of tides. We use the octupolar non-restricted approximation for the orbital interactions, general relativity corrections, the quadrupolar approximation for the spins, and the viscous linear model for tides. We derive the averaged equations of motion in a simplified vectorial formalism, which is suitable to model the long-term evolution of a wide variety of circumbinary systems in very eccentric and inclined orbits. In particular, this vectorial approach can be used to derive constraints for tidal migration, capture in Cassini states, and stellar spin-orbit misalignment. We show that circumbinary planets with initial arbitrary orbital inclination can become coplanar through a secular resonance between the precession of the orbit and the precession of the spin of one of the stars. We also show that circumbinary systems for which the pericenter of the inner orbit is initially in libration present chaotic motion for the spins ...

  19. Stellar Tidal Streams in External Galaxies

    CERN Document Server

    Carlin, Jeffrey L; Martinez-Delgado, David; Gabany, R Jay

    2016-01-01

    To place the highly substructured stellar halos of the Milky Way and M31 in a larger context of hierarchical galaxy formation, it is necessary to understand the prevalence and properties of tidal substructure around external galaxies. This chapter details the current state of our observational knowledge of streams in galaxies in and beyond the Local Group, which are studied both in resolved stellar populations and in integrated light. Modeling of individual streams in extragalactic systems is hampered by our inability to obtain resolved stellar kinematics in the streams, though many streams contain alternate luminous kinematic tracers, such as globular clusters or planetary nebulae. We compare the observed structures to the predictions of models of galactic halo formation, which provide insight in the number and properties of streams expected around Milky Way like galaxies. More specifically, we discuss the inferences that can be made about stream progenitors based only on observed morphologies. We expand our...

  20. Disc formation from stellar tidal disruptions

    CERN Document Server

    Bonnerot, Clément; Lodato, Giuseppe; Price, Daniel J

    2015-01-01

    The potential of tidal disruption of stars to probe otherwise quiescent supermassive black holes cannot be exploited, if their dynamics is not fully understood. So far, the observational appearance of these events has been commonly derived from analytical extrapolations of the debris dynamical properties just after the stellar disruption. In this paper, we perform hydrodynamical simulations of stars in highly eccentric orbits, that follow the stellar debris after disruption and investigate their ultimate fate. We demonstrate that gas debris circularize on an orbital timescale because relativistic apsidal precession causes the stream to self-cross. The higher the eccentricity and/or the deeper the encounter, the faster is the circularization. If the internal energy deposited by shocks during stream self-interaction is readily radiated, the gas forms a narrow ring at the circularization radius. It will then proceed to accrete viscously at a super-Eddington rate, puffing up under radiation pressure. If instead c...

  1. Metabolomic Analyses of Brain Tissue in Sepsis Induced by Cecal Ligation Reveal Specific Redox Alterations-Protective Effects of the Oxygen Radical Scavenger Edaravone

    DEFF Research Database (Denmark)

    Hara, Naomi; Chijiiwa, Miyuki; Yara, Miki

    2015-01-01

    (Bcl-2 and Bax) were analyzed in selected brain regions. CLPE showed significant improvement in survival compared with CLPV 18 h postinduction of sepsis (P death in both parietal cortex...... at analyzing the preventive effect of the free radical scavenger edaravone on sepsis-induced brain alterations. Sepsis was induced by cecal ligation and puncture (CLP) and the mice were divided into three groups-CLP vehicle (CLPV), CLP and edaravone (MCI-186, 3-methyl-1-phenyl-2-pyrazolin-5-one) (CLPE...... induced by cecal ligation alters cerebral redox status and supports a proapoptotic phenotype. The free radical scavenger edavarone reduces mortality of septic mice and protects against sepsis-induced neuronal cell death....

  2. Tidal Downsizing model. I. Numerical methods: saving giant planets from tidal disruptions

    CERN Document Server

    Nayakshin, Sergei

    2014-01-01

    Tidal Downsizing (TD) is a recently developed planet formation theory that supplements the classical Gravitational disc Instability (GI) model with planet migration inward and tidal disruptions of GI fragments in the inner regions of the disc. Numerical methods for a detailed population synthesis of TD planets are presented here. As an example application, the conditions under which GI fragments collapse faster than they migrate into the inner $a\\sim$ few AU disc are considered. It is found that most gas fragments are tidally or thermally disrupted unless (a) their opacity is $\\sim 3$ orders of magnitude less than the interstellar dust opacity at metallicities typical of the observed giant planets, or (b) the opacity is high but the fragments accrete large dust grains (pebbles) from the disc. Case (a) models produce very low mass solid cores ($M_{\\rm core} < 0.1$ Earth masses) and follow a negative correlation of giant planet frequency with host star metallicity. In contrast, case (b) models produce massiv...

  3. Tidal River Management (TRM and Tidal Basin Management (TBM: A case study on Bangladesh

    Directory of Open Access Journals (Sweden)

    Talchabhadel Rocky

    2016-01-01

    Full Text Available Bangladesh is the biggest delta of the world. Construction of numbers of polders is one of the flood resilient approach. But the presence of coastal polders de-linked the flood plain. The siltation in river causes riverbeds to become higher than the adjacent crop lands, and vast area under the polders became permanently water logged rendering large tract of land uncultivable. The current practice is temporarily de-poldering by cutting embankment. This is a natural water management process with very little human interventions but it needs strong participation and consensus with a great deal of sacrifice by the stakeholders for a specific period (3 to 5 years or even more[1]. An attempt has been made to study the phenomena of tidal basin management reviewing some secondary data and processes involved in successfully operated tidal basins of Bangladesh. And preliminary laboratory experiments are carried out to precisely look into the suspended sediment transport. With varying outflow discharge and sediment supply, the transport processes are investigated. 3D sediment transport model developed using openFOAM has good agreement with experimental result and can be used to better understand effectiveness of tidal basin management.

  4. Palomar 5 and its Tidal Tails: A Search for New Members in the Tidal Stream

    CERN Document Server

    Kuzma, Pete; Keller, Stefan; Maunder, Elizabeth

    2014-01-01

    In this paper we present the results of a search for members of the globular cluster Palomar 5 and its associated tidal tails. The analysis has been performed using intermediate and low resolution spectroscopy with the AAOmega spectrograph on the Anglo-Australian Telescope. Based on kinematics, line strength and photometric information, we identify 39 new red giant branch stars along $\\sim$20$^{\\circ}$ of the tails, a larger angular extent than has been previously studied. We also recover eight previously known tidal tail members. Within the cluster, we find seven new red giant and one blue horizontal branch members and confirm a further twelve known red giant members. In total, we provide velocity data for 67 stars in the cluster and the tidal tails. Using a maximum likelihood technique, we derive a radial velocity for Pal 5 of $-57.4 \\pm 0.3$ km s$^{-1}$ and a velocity dispersion of $1.2\\pm0.3$ km s$^{-1}$. We confirm and extend the linear velocity gradient along the tails of $1.0 \\pm 0.1$ km s$^{-1}$ deg$^...

  5. TIDALLY DRIVEN DYNAMOS IN A ROTATING SPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Cébron, D.; Hollerbach, R., E-mail: david.cebron@ujf-grenoble.fr, E-mail: r.hollerbach@leeds.ac.uk [Institut für Geophysik, Sonneggstrasse 5, ETH Zürich, Zürich CH-8092 (Switzerland)

    2014-07-01

    Large-scale planetary or stellar magnetic fields generated by a dynamo effect are mostly attributed to flows forced by buoyancy forces in electrically conducting fluid layers. However, these large-scale fields may also be controlled by tides, as previously suggested for the star τ-boo, Mars, or the early Moon. By simulating a small local patch of a rotating fluid, Barker and Lithwick have recently shown that tides can drive small-scale dynamos by exciting a hydrodynamic instability, the so-called elliptical (or tidal) instability. By performing global magnetohydrodynamic simulations of a rotating spherical fluid body, we investigate if this instability can also drive the observed large-scale magnetic fields. We are thus interested in the dynamo threshold and the generated magnetic field in order to test if such a mechanism is relevant for planets and stars. Rather than solving the problem in a geometry deformed by tides, we consider a spherical fluid body and add a body force to mimic the tidal deformation in the bulk of the fluid. This allows us to use an efficient spectral code to solve the magnetohydrodynamic problem. We first compare the hydrodynamic results with theoretical asymptotic results and numerical results obtained in a truly deformed ellipsoid, which confirms the presence of elliptical instability. We then perform magnetohydrodynamic simulations and investigate the dynamo capability of the flow. Kinematic and self-consistent dynamos are finally simulated, showing that the elliptical instability is capable of generating a dipole-dominated large-scale magnetic field in global simulations of a fluid rotating sphere.

  6. Tidal constraints on the interior of Venus

    Science.gov (United States)

    Dumoulin, Caroline; Tobie, Gabriel; Verhoeven, Olivier; Rosenblatt, Pascal; Rambaux, Nicolas

    2016-10-01

    As a prospective study for a future exploration of Venus, we propose to systematically investigate the signature of the internal structure in the gravity field and the rotation state of Venus, through the determination of the moment of inertia and the tidal Love number.We test various mantle compositions, core size and density as well as temperature profiles representative of different scenarios for formation and evolution of Venus. The mantle density ρ and seismic vP and vS wavespeeds are computed in a consistent manner from given temperature and composition using the Perple X program. This method computes phase equilibria and uses the thermodynamics of mantle minerals developped by Stixrude and Lithgow-Bertelloni (2011).The viscoelastic deformation of the planet interior under the action of periodic tidal forces are computed following the method of Tobie et al. (2005).For a variety of interior models of Venus, the Love number, k2, and the moment of inertia factor are computed following the method described above. The objective is to determine the sensitivity of these synthetic results to the internal structure. These synthetic data are then used to infer the measurement accuracies required on the time-varying gravitational field and the rotation state (precession rate, nutation and length of day variations) to provide useful constraints on the internal structure.We show that a better determination of k2, together with an estimation of the moment of inertia, the radial displacement, and of the time lag, if possible, will refine our knowledge on the present-day interior of Venus (size of the core, mantle temperature, composition and viscosity). Inferring these quantities from a future ex- ploration mission will provide essential constraints on the formation and evolution scenarios of Venus.

  7. A bright year for tidal disruptions

    Science.gov (United States)

    Metzger, Brian D.; Stone, Nicholas C.

    2016-09-01

    When a star is tidally disrupted by a supermassive black hole (SMBH), roughly half of its mass falls back to the SMBH at super-Eddington rates. As this gas is tenuously gravitationally bound and unable to cool radiatively, only a small fraction fin ≪ 1 may accrete, with the majority instead becoming unbound in an outflow of velocity ˜104 km s-1. The outflow spreads laterally as it expands to large radii, encasing the SMBH and blocking the inner disc's EUV/X-ray radiation, which becomes trapped in a radiation-dominated nebula. Ionizing nebular radiation heats the inner edge of the ejecta, converting the emission to optical/near-UV wavelengths where photons more readily escape due to the lower opacity. This can explain the unexpectedly low and temporally constant effective temperatures of optically discovered tidal disruption event (TDE) flares. For high-mass SMBHs, M• ≳ 107 M⊙, the ejecta can become fully ionized at an earlier stage, or for a wider range of viewing angles, producing a TDE flare accompanied by thermal X-ray emission. The peak optical luminosity is suppressed as the result of adiabatic losses in the inner disc wind when M• ≪ 107 M⊙, possibly contributing to the unexpected dearth of optical TDEs in galaxies with low-mass SMBHs. In the classical picture, where fin ≈ 1, TDEs de-spin supermassive SMBHs and cap their maximum spins well below theoretical accretion physics limits. This cap is relaxed in our model, and existing Fe Kα spin measurements provide preliminary evidence that fin < 1.

  8. Influence of the Interior Properties of Mercury on Its Tidal Response (Invited)

    Science.gov (United States)

    Padovan, S.; Margot, J.; Hauck, S. A.; Moore, W. B.; Solomon, S. C.

    2013-12-01

    Dynamical measurements currently yield the only direct constraints on the interior structure of Mercury. The combination of Mercury's second-harmonic-degree gravitational coefficients J2 and C22, along with the measured obliquity and libration amplitude, provide the moment of inertia of the planet, C, and the moment of inertia of its outer solid shell, Cm. Models of the interior structure constrained by the bulk density ρ, C, and Cm provide information on the radius of the liquid core and of the mean density of material below and above that radius. The response of Mercury to the differential gravitational pull of the Sun, i.e., the solid-body tide, depends on the physical properties of the subsurface materials and can provide an additional constraint on the interior of the planet. The solid-body tide induces a periodic variation of the gravitational field, of which the largest component (degree 2) is parameterized through the complex Love number k2. By modeling Mercury's internal structure as a set of homogenous, spherically symmetric layers with Maxwell rheology, we calculate k2 for a suite of interior structure models compatible with ρ, C, and Cm. Results show that the measurement of the real component of k2 can improve the determination of both the radius of the liquid core and the mean density of the material below the outer solid shell and can provide an indication of the rigidity of the outer solid shell. A set of models with a solid FeS layer at the top of the liquid core is compatible both with the geochemical evidence collected by MESSENGER and with the dynamical constraints. The elastic properties of this layer are markedly different from those of the overlying silicate mantle and crust, with the effect of modifying the tidal response. Thus the measurement of k2 represents an avenue to test for the presence of such an FeS layer. The imaginary part of k2 relates directly to the energy dissipation induced by the tidal deformation. The choice of interior

  9. Intrinsic alignment contamination to CMB lensing-galaxy weak lensing correlations from tidal torquing

    Science.gov (United States)

    Larsen, Patricia; Challinor, Anthony

    2016-10-01

    Correlations of galaxy ellipticities with large-scale structure, due to galactic tidal interactions, provide a potentially significant contaminant to measurements of cosmic shear. However, these intrinsic alignments are still poorly understood for galaxies at the redshifts typically used in cosmic shear analyses. For spiral galaxies, it is thought that tidal torquing is significant in determining alignments resulting in zero correlation between the intrinsic ellipticity and the gravitational potential in linear theory. Here, we calculate the leading-order correction to this result in the tidal-torque model from non-linear evolution, using second-order perturbation theory, and relate this to the contamination from intrinsic alignments to the recently measured cross-correlation between galaxy ellipticities and the cosmic microwave background (CMB) lensing potential. On the scales relevant for CMB lensing observations, the squeezed limit of the gravitational bispectrum dominates the correlation. Physically, the large-scale mode that sources CMB lensing modulates the small-scale power and hence the intrinsic ellipticity, due to non-linear evolution. We find that the angular cross-correlation from tidal torquing has a very similar scale dependence as in the linear alignment model, believed to be appropriate for elliptical galaxies. The amplitude of the cross-correlation is predicted to depend strongly on the formation redshift, being smaller for galaxies that formed at higher redshift when the bispectrum of the gravitational potential was smaller. Finally, we make simple forecasts for constraints on intrinsic alignments from the correlation of forthcoming cosmic shear measurements with current CMB lensing measurements. We note that cosmic variance can be significantly reduced in measurements of the difference in the intrinsic alignments for elliptical and spiral galaxies if these types can be separated (e.g. using colour).

  10. Tidal dynamics of the Terminos Lagoon, Mexico: observations and 3D numerical modelling

    Science.gov (United States)

    Contreras Ruiz Esparza, Adolfo; Douillet, Pascal; Zavala-Hidalgo, Jorge

    2014-09-01

    The tidal circulation patterns in the Terminos Lagoon were studied based on the analysis of 1 year of measurements and numerical simulations using a baroclinic 3D hydrodynamic model, the MARS3D. A gauging network was installed consisting of six self-recording pressure-temperature sensors, a tide gauge station and two current profilers, with pressure and temperature sensors moored in the main lagoon inlets. Model simulations were validated against current and sea level observations and were used to analyse the circulation patterns caused by the tidal forcing. The numerical model was forced with eight harmonic components, four diurnal ( K 1, O 1, P 1, Q 1) and four semi-diurnal ( M 2, S 2, N 2, K 2), extracted from the TPX0.7 database. The tidal patterns in the study area vary from mixed, mainly diurnal in the two main inlets of the lagoon, to diurnal in its interior. The tidal residual circulation inside the lagoon is dominated by a cyclonic gyre. The results indicate a net flux from the southwest Ciudad del Carmen inlet (CdC) towards the northeast Puerto Real inlet (PtR) along the southern side of the lagoon and the opposite in the northern side. The results indicate two areas of strong currents in the vicinity of the inlets and weak currents inside the lagoon. The area of strong currents in the vicinity of the CdC inlet is larger than that observed in the PtR inlet. Nevertheless, the current analysis indicates that the highest current speeds, which can reach a magnitude of 1.9 m s-1, occurred in PtR. A further analysis of the tide distortion in the inlets revealed that both passages are ebb dominated.

  11. Structural Design of a Horizontal-Axis Tidal Current Turbine Composite Blade

    Energy Technology Data Exchange (ETDEWEB)

    Bir, G. S.; Lawson, M. J.; Li, Y.

    2011-10-01

    This paper describes the structural design of a tidal composite blade. The structural design is preceded by two steps: hydrodynamic design and determination of extreme loads. The hydrodynamic design provides the chord and twist distributions along the blade length that result in optimal performance of the tidal turbine over its lifetime. The extreme loads, i.e. the extreme flap and edgewise loads that the blade would likely encounter over its lifetime, are associated with extreme tidal flow conditions and are obtained using a computational fluid dynamics (CFD) software. Given the blade external shape and the extreme loads, we use a laminate-theory-based structural design to determine the optimal layout of composite laminas such that the ultimate-strength and buckling-resistance criteria are satisfied at all points in the blade. The structural design approach allows for arbitrary specification of the chord, twist, and airfoil geometry along the blade and an arbitrary number of shear webs. In addition, certain fabrication criteria are imposed, for example, each composite laminate must be an integral multiple of its constituent ply thickness. In the present effort, the structural design uses only static extreme loads; dynamic-loads-based fatigue design will be addressed in the future. Following the blade design, we compute the distributed structural properties, i.e. flap stiffness, edgewise stiffness, torsion stiffness, mass, moments of inertia, elastic-axis offset, and center-of-mass offset along the blade. Such properties are required by hydro-elastic codes to model the tidal current turbine and to perform modal, stability, loads, and response analyses.

  12. User-Friendly Predictive Modeling of Greenhouse Gas (GHG) Fluxes and Carbon Storage in Tidal Wetlands

    Science.gov (United States)

    Ishtiaq, K. S.; Abdul-Aziz, O. I.

    2015-12-01

    We developed user-friendly empirical models to predict instantaneous fluxes of CO2 and CH4 from coastal wetlands based on a small set of dominant hydro-climatic and environmental drivers (e.g., photosynthetically active radiation, soil temperature, water depth, and soil salinity). The dominant predictor variables were systematically identified by applying a robust data-analytics framework on a wide range of possible environmental variables driving wetland greenhouse gas (GHG) fluxes. The method comprised of a multi-layered data-analytics framework, including Pearson correlation analysis, explanatory principal component and factor analyses, and partial least squares regression modeling. The identified dominant predictors were finally utilized to develop power-law based non-linear regression models to predict CO2 and CH4 fluxes under different climatic, land use (nitrogen gradient), tidal hydrology and salinity conditions. Four different tidal wetlands of Waquoit Bay, MA were considered as the case study sites to identify the dominant drivers and evaluate model performance. The study sites were dominated by native Spartina Alterniflora and characterized by frequent flooding and high saline conditions. The model estimated the potential net ecosystem carbon balance (NECB) both in gC/m2 and metric tonC/hectare by up-scaling the instantaneous predicted fluxes to the growing season and accounting for the lateral C flux exchanges between the wetlands and estuary. The entire model was presented in a single Excel spreadsheet as a user-friendly ecological engineering tool. The model can aid the development of appropriate GHG offset protocols for setting monitoring plans for tidal wetland restoration and maintenance projects. The model can also be used to estimate wetland GHG fluxes and potential carbon storage under various IPCC climate change and sea level rise scenarios; facilitating an appropriate management of carbon stocks in tidal wetlands and their incorporation into a

  13. A comparative study of physical and numerical modeling of tidal network ontogeny

    Science.gov (United States)

    Zhou, Zeng; Olabarrieta, Maitane; Stefanon, Luana; D'Alpaos, Andrea; Carniello, Luca; Coco, Giovanni

    2014-04-01

    We investigate the initiation and long-term evolution of tidal networks by comparing controlled laboratory experiments and their associated scaling laws with outputs from a numerical model. We conducted numerical experiments at both the experimental laboratory scale (ELS) and natural estuary scale (NES) and compared these simulations with experimental data and field observations. Sensitivity tests show that initial bathymetry, frictional parametrization, sediment transport, and bed slope terms play an important role in determining the morphodynamic evolution and the final landscape. Consistent with experimental observations, the morphodynamic feedbacks between flow, sediment transport, and bathymetry gradually lead the system to a less dynamic state, finally reaching a stable network configuration. In both the ELS and NES simulations, the initially planar lagoon with large intertidal areas is subject to erosion, indicating ebb-dominance. Based on quantitative analyses of the ELS and the NES simulations (e.g., geometric characteristics and relationship between modified tidal prism and cross-sectional area), we conclude that numerical simulations are consistent with laboratory experiments and show that both type of models provide a realistic, albeit simplified, representation of natural systems. The combination of laboratory and numerical experiments also allowed us to explore the possibility of reaching a long-term morphodynamic equilibrium. Both the physical and numerical models approach a dynamic equilibrium characterized by negligible gradients in sediment fluxes. The equilibrium configuration appears to be consistent with traditional relationships linking tidal prism and cross-sectional area of the inlet. Finally, this contribution highlights the significance of complementary research between experimental and numerical modeling in investigating long-term morphodynamics of tidal networks.

  14. Vertical Distribution of Tidal Flow Reynolds Stress in Shallow Sea

    Institute of Scientific and Technical Information of China (English)

    SONG Zhi-yao; NI Zhi-hui; LU Guo-nian

    2009-01-01

    Based on the results of the tidal flow Reynolds stresses of the field observations,indoor experiments,and numerical models,the parabolic distribution of the tidal flow Reynolds stress is proposed and its coefficients are determined theoretically in this paper.Having been well verified with the field data and experimental data,the proposed distribution of Reynolds stress is also compared with numerical model results,and a good agreement is obtained,showing that this distribution can well reflect the basic features of Reynolds stress deviating from the linear distribution that is downward when the tidal flow is of acceleration,upward when the tidal flow is of deceleration.Its dynamics cause is also discussed preliminarily and the influence of the water depth is pointed out from the definition of Reynolds stress,turbulent generation,transmission,and so on.The established expression for the vertical distribution of the tidal flow Reynolds stress is not only simple and explicit,but can also well reflect the features of the tidal flow acceleration and deceleration for further study on the velocity profile of tidal flow.

  15. A summary of the San Francisco tidal wetlands restoration series

    Directory of Open Access Journals (Sweden)

    Larry R. Brown

    2003-10-01

    Full Text Available The four topical articles of the Tidal Wetlands Restoration Series summarized and synthesized much of what is known about tidal wetlands and tidal wetland restoration in the San Francisco Estuary (hereafter “Estuary”. Despite a substantial amount of available information, major uncertainties remain. A major uncertainty with regard to fishes is the net benefit of restored tidal wetlands relative to other habitats for native fishes in different regions of the Estuary given the presence of numerous invasive alien species. With regard to organic carbon, a major uncertainty is the net benefit of land use change given uncertainty about the quantity and quality of different forms of organic carbon resulting from different land uses. A major challenge is determining the flux of organic carbon from open systems like tidal wetlands. Converting present land uses to tidal wetlands will almost certainly result in increased methylation of mercury at the local scale with associated accumulation of mercury within local food webs. However, it is unclear if such local accumulation is of concern for fish, wildlife or humans at the local scale or if cumulative effects at the regional scale will emerge. Based on available information it is expected that restored tidal wetlands will remain stable once constructed; however, there is uncertainty associated with the available data regarding the balance of sediment accretion, sea-level rise, and sediment erosion. There is also uncertainty regarding the cumulative effect of many tidal restoration projects on sediment supply. The conclusions of the articles highlight the need to adopt a regional and multidisciplinary approach to tidal wetland restoration in the Estuary. The Science Program of the CALFED effort provides an appropriate venue for addressing these issues.

  16. Constraining Tidal Dissipation in Stars and Destruction Rates of Exoplanets

    Science.gov (United States)

    Jackson, Brian; Penev, K.; Barnes, R.

    2011-01-01

    Several recent studies have shown that the orbits of most transiting extra-solar planets, with periods of order a few days, are not stable against tidal decay. If the host star rotates slowly enough, tidal dissipation within the star causes the planet to spiral in over many millions or billions of years. Because the rate of tidal decay increases rapidly as orbital semi-major axis drops, planets that start out very close to their host stars are quickly destroyed, while planets farther out require more time. We calculate the times left for known transiting exoplanets as a function of the rate of tidal dissipation within the host star. For a population of such planets, we expect to observe a minority of planets near the end of their lives since those planets will only survive for a short time more. For an assumed tidal dissipation rate, if we find instead that a majority of transiting planets have only a small fraction of the lifetimes left before destruction, we can conclude the assumed tidal dissipation rate is too large. Thus, we can estimate the rate of tidal dissipation within planet-hosting stars by considering the distributions of times left of transiting planets for a range of assumed dissipation rates. We must also account for important selection and observational biases. Our results based on such an analysis suggest stellar dissipation rates corresponding to tidal Q-values of 106 and larger are consistent with observations, while values of 105 and smaller are not. Given these constraints, we estimate the rates of tidal destruction of transiting exoplanets.

  17. Tidal propagation and dissipation in the Taiwan Strait

    Science.gov (United States)

    Yu, Haiqing; Yu, Huaming; Wang, Lu; Kuang, Liang; Wang, Hui; Ding, Yang; Ito, Shin-ichi; Lawen, Johannes

    2017-03-01

    Previous research on tides and tidal dynamics in the Taiwan Strait (TS) is reviewed in this paper. Tidal dynamics, which is the basic and dominant hydrodynamics in this area, attracts much interest in the last 30 years and till now its physical mechanism is still in debate. In this study, the major research methods and findings of previous works on barotropic tides in the TS are summarized. Based on Finite Volume Coastal Ocean Model (FVCOM), the main tidal constituents (M2, S2, K1, O1) are well simulated with the mean root-mean-square (RMS) errors of 4.7, 2.0, 1.3 and 0.7 cm between the observed and simulated tidal constants, respectively. It has been proved that semi-diurnal tidal movement is mainly determined by the waves from the East China Sea (ECS), while waves from the ECS and the Luzon Strait (LS) play comparable roles in diurnal tidal movement in the TS by linear superposition and the interaction of these two waves is the main cause for the progressive diurnal tidal waves in the TS. Furthermore, energy analysis revealed that the M2 tidal wave system in the TS and its adjacent area south to the shoal is an standing wave system and the anti-node appears in the central TS while the wave node locates in the shoal area, which can be contributed to the interaction of the incident waves from the ECS and the topography step south to Taiwan island, while the shoal also has an impact on the whole semi-diurnal tidal wave system in the TS. This standing wave system is consistent with the little energy dissipation in the central TS and much energy dissipation in the southern TS, where the shallow water effect also contributes to the local dissipation to some extent.

  18. Tidal Heating in a Magma Ocean within Jupiter's Moon Io

    Science.gov (United States)

    Tyler, Robert H.; Henning, Wade G.; Hamilton, Christopher W.

    2015-06-01

    Active volcanism observed on Io is thought to be driven by the temporally periodic, spatially differential projection of Jupiter's gravitational field over the moon. Previous theoretical estimates of the tidal heat have all treated Io as essentially a solid, with fluids addressed only through adjustment of rheological parameters rather than through appropriate extension of the dynamics. These previous estimates of the tidal response and associated heat generation on Io are therefore incomplete and possibly erroneous because dynamical aspects of the fluid behavior are not permitted in the modeling approach. Here we address this by modeling the partial-melt asthenosphere as a global layer of fluid governed by the Laplace Tidal Equations. Solutions for the tidal response are then compared with solutions obtained following the traditional solid-material approach. It is found that the tidal heat in the solid can match that of the average observed heat flux (nominally 2.25 W m-2), though only over a very restricted range of plausible parameters, and that the distribution of the solid tidal heat flux cannot readily explain a longitudinal shift in the observed (inferred) low-latitude heat fluxes. The tidal heat in the fluid reaches that observed over a wider range of plausible parameters, and can also readily provide the longitudinal offset. Finally, expected feedbacks and coupling between the solid/fluid tides are discussed. Most broadly, the results suggest that both solid and fluid tidal-response estimates must be considered in exoplanet studies, particularly where orbital migration under tidal dissipation is addressed.

  19. Tidally Induced Offset Disks in Magellanic Spiral Galaxies

    Science.gov (United States)

    Pardy, Stephen A.; D'Onghia, Elena; Athanassoula, E.; Wilcots, Eric M.; Sheth, Kartik

    2016-08-01

    Magellanic spiral galaxies are a class of one-armed systems that often exhibit an offset stellar bar and are rarely found around massive spiral galaxies. Using a set of N-body and hydrodynamic simulations, we consider a dwarf-dwarf galaxy interaction as the driving mechanism for the formation of this peculiar class of systems. We investigate here the relation between the dynamical, stellar, and gaseous disk center and the bar. In all our simulations the bar center always coincides with the dynamical center, while the stellar disk becomes highly asymmetric during the encounter, causing the photometric center of the Magellanic galaxy disk to become mismatched with both the bar and the dynamical center. The disk asymmetries persist for almost 2 Gyr, the time that it takes for the disk to be recentered with the bar, and well after the companion has passed. This explains the nature of the offset bar found in many Magellanic-type galaxies, including the Large Magellanic Cloud (LMC) and NGC 3906. In particular, these results, once applied to the LMC, suggest that the dynamical center should reside in the bar center instead of the H i center as previously assumed, pointing to a variation in the current estimate of the north component of the LMC proper motion.

  20. Evaluation of streambed scour at bridges over tidal waterways in Alaska

    Science.gov (United States)

    Conaway, Jeffrey S.; Schauer, Paul V.

    2012-01-01

    The potential for streambed scour was evaluated at 41 bridges that cross tidal waterways in Alaska. These bridges are subject to several coastal and riverine processes that have the potential, individually or in combination, to induce streambed scour or to damage the structure or adjacent channel. The proximity of a bridge to the ocean and water-surface elevation and velocity data collected over a tidal cycle were criteria used to identify the flow regime at each bridge, whether tidal, riverine, or mixed, that had the greatest potential to induce streambed scour. Water-surface elevations measured through at least one tide cycle at 32 bridges were correlated to water levels at the nearest tide station. Asymmetry of the tidal portion of the hydrograph during the outgoing tide at 12 bridges indicated that riverine flows were stored upstream of the bridge during the tidal exchange. This scenario results in greater discharges and velocities during the outgoing tide compared to those on the incoming tide. Velocity data were collected during outgoing tides at 10 bridges that experienced complete flow reversals, and measured velocities during the outgoing tide exceeded the critical velocity required to initiate sediment transport at three sites. The primary risk for streambed scour at most of the sites considered in this study is from riverine flows rather than tidal fluctuations. A scour evaluation for riverine flow was completed at 35 bridges. Scour from riverine flow was not the primary risk for six tidally-controlled bridges and therefore not evaluated at those sites. Field data including channel cross sections, a discharge measurement, and a water-surface slope were collected at the 35 bridges. Channel instability was identified at 14 bridges where measurable scour and or fill were noted in repeated surveys of channel cross sections at the bridge. Water-surface profiles for the 1-percent annual exceedance probability discharge were calculated by using the Hydrologic

  1. Effects of tidal interactions on the gas flows of elliptical galaxies

    CERN Document Server

    D'Ercole, A; Ciotti, L

    1999-01-01

    During a Hubble time, cluster galaxies may undergo several mutual encounters close enough to gravitationally perturb their hot, X-ray emitting gas flows. We ran several 2D, time dependent hydrodynamical models to investigate the effects of such perturbations on the gas flow inside elliptical galaxies. In particular, we studied in detail the modifications occurring in the scenario proposed by D'Ercole et al. (1989), in which the galactic interstellar medium produced by the aging galactic stellar population, is heated by SNIa at a decreasing rate. We find that, although the tidal interaction in our models lasts less than 1 Gyr, its effect extends over several Gyrs. The tidally induced turbulent flows create dense filaments which cool quickly and accrete onto the galactic center, producing large spikes in the global Lx. Once this mechanism starts, it is fed by gravity and amplified by SNIa. In cooling flow models without supernovae the amplitude of the Lx fluctuations due to the tidal interaction is substantiall...

  2. Tidal Triggering and Statistical Patterns of Microseismicity at Axial Volcano on the Juan de Fuca Ridge

    Science.gov (United States)

    Bohnenstiehl, D. R.; Dziak, R. P.; Caplan-Auerbach, J.; Haxel, J. H.; Mann, M. E.; Pennington, C.; Weis, J.; Womack, N.; Levy, S.

    2015-12-01

    Tidal stress changes are known to modulate the timing of microearthquakes within many mid-ocean ridge volcanic systems. At Axial Volcano, located on the Juan de Fuca Ridge, earthquakes occur preferentially when volumetric extension peaks near times of low ocean tide. Autonomous ocean-bottom hydrophone (OBH, 2007-2011) and cabled ocean bottom seismometer (OBS, Nov. 2014-) data are used to quantify the strength of tidal triggering in time periods before the April 2011 and April 2015 eruptions at Axial Volcano. The mean percent excess at times of low ocean-tide is ~14% (16% std) in the four years prior to the 2011 eruption and ~18% (17% std) in the five months prior to the 2015 eruption. The sensitivity of earthquakes to tidal stress does not evolve systematically prior to either eruption; however, this pattern is disturbed by much larger stress changes associated with the onset of dike intrusion. Following dike injection and eruption, seismicity rates drop sharply. As seismicity rates continue to rise in the months following the 2015 eruption, real-time data available from the cabled OBS network will be used quantify temporal patterns in microearthquake activity as dike induced stresses are relaxed and the magma chamber inflates.

  3. Impact of vegetation die-off on spatial flow patterns over a tidal marsh

    Science.gov (United States)

    Temmerman, Stijn; Moonen, Pieter; Schoelynck, Jonas; Govers, Gerard; Bouma, Tjeerd J.

    2012-02-01

    Large-scale die-off of tidal marsh vegetation, caused by global change, is expected to change flow patterns over tidal wetlands, and hence to affect valuable wetland functions such as reduction of shoreline erosion, attenuation of storm surges, and sedimentation in response to sea level rise. This study quantified for the first time the effects of large-scale (4 ha) artificial vegetation removal, as proxy of die-off, on the spatial flow patterns through a tidal marsh channel and over the surrounding marsh platform. After vegetation removal, the flow velocities measured on the platform increased by a factor of 2 to 4, while the channel flow velocities decreased by almost a factor of 3. This was associated with a change in flow directions on the platform, from perpendicular to the channel edges when vegetation was present, to a tendency of more parallel flow to the channel edges when vegetation was absent. Comparison with hydrodynamic model simulations explains that the vegetation-induced friction causes both flow reduction on the vegetated platform and flow acceleration towards the non-vegetated channels. Our findings imply that large-scale vegetation die-off would not only result in decreased platform sedimentation rates, but also in sediment infilling of the channels, which together would lead to further worsening of plant growth conditions and a potentially runaway feedback to permanent vegetation loss.

  4. Pacific deep circulation and ventilation controlled by tidal mixing away from the sea bottom.

    Science.gov (United States)

    Oka, Akira; Niwa, Yoshihiro

    2013-01-01

    Vertical mixing in the ocean is a key driver of the global ocean thermohaline circulation, one of the most important factors controlling past and future climate change. Prior observational and theoretical studies have focused on intense tidal mixing near the sea bottom (near-field mixing). However, ocean general circulation models that employ a parameterization of near-field mixing significantly underestimate the strength of the Pacific thermohaline circulation. Here we demonstrate that tidally induced mixing away from the sea bottom (far-field mixing) is essential in controlling the Pacific thermohaline circulation. Via the addition of far-field mixing to a widely used tidal parameterization, we successfully simulate the Pacific thermohaline circulation. We also propose that far-field mixing is indispensable for explaining the presence of the world ocean's oldest water in the eastern North Pacific Ocean. Our findings suggest that far-field mixing controls ventilation of the deep Pacific Ocean, a process important for ocean carbon and biogeochemical cycles.

  5. Tidal deformability and I-Love-Q relations for gravastars with polytropic thin shells

    CERN Document Server

    Uchikata, Nami; Pani, Paolo

    2016-01-01

    The moment of inertia, the spin-induced quadrupole moment, and the tidal Love number of neutron-star and quark-star models are related through some relations which depend only mildly on the stellar equation of state. These "I-Love-Q" relations have important implications for astrophysics and gravitational-wave astronomy. An interesting problem is whether similar relations hold for other compact objects and how they approach the black-hole limit. To answer these questions, here we investigate the deformation properties of a large class of thin-shell gravastars, which are exotic compact objects that do not possess an event horizon nor a spacetime singularity. Working in a small-spin and small-tidal field expansion, we calculate the moment of inertia, the quadrupole moment, and the (quadrupolar electric) tidal Love number of gravastars with a polytropic thin shell. The I-Love-Q relations of a thin-shell gravastar are drastically different from those of an ordinary neutron star. The Love number and quadrupole mom...

  6. Constraints on dissipation in the deep interiors of Ganymede and Europa from tidal phase-lags

    Science.gov (United States)

    Hussmann, Hauke; Shoji, Daigo; Steinbrügge, Gregor; Stark, Alexander; Sohl, Frank

    2016-11-01

    Jupiter's satellites are subject to strong tidal forces which result in variations of the gravitational potential and deformations of the satellites' surfaces on the diurnal tidal cycle. Such variations are described by the Love numbers k_2 and h_2 for the tide-induced potential variation due to internal mass redistribution and the radial surface displacement, respectively. The phase-lags φ _{k_2} and φ _{h_2} of these complex numbers contain information about the rheological and dissipative states of the satellites. Starting from interior structure models and assuming a Maxwell rheology to compute the tidal deformation, we calculate the phase-lags in application to Ganymede and Europa. For both satellites we assume a decoupling of the outer ice-shell from the deep interior by a liquid subsurface water ocean. We show that, in this case, the phase-lag difference Δ φ = φ _{k_2}- φ _{h_2} can provide information on the rheological and thermal state of the deep interiors if the viscosities of the deeper layers are small. In case of Ganymede, phase-lag differences can reach values of a few degrees for high-pressure ice viscosities {Jupiter Icy Moons Explorer (JUICE) and NASA's Europa Multiple Flyby Mission, both targeted for the Jupiter system.

  7. Stellar dynamics and tidal disruption events in galactic nuclei

    CERN Document Server

    Alexander, Tal

    2012-01-01

    The disruption of a star by the tidal field of a massive black hole is the final outcome of a chain of complex dynamical processes in the host galaxy. I introduce the "loss cone problem", and describe the many theoretical and numerical challenges on the path of solving it. I review various dynamical channels by which stars can be supplied to a massive black hole, and the relevant dynamical relaxation / randomization mechanisms. I briefly mention some "exotic" tidal disruption scenarios, and conclude by discussing some new dynamical results that are changing our understanding of dynamics near a massive black hole, and may well be relevant for tidal disruption dynamics.

  8. Dynamics of tidally captured planets in the Galactic Center

    CERN Document Server

    Trani, Alessandro Alberto; Spera, Mario; Bressan, Alessandro

    2016-01-01

    Recent observations suggest ongoing planet formation in the innermost parsec of our Galaxy. The super-massive black hole (SMBH) might strip planets or planetary embryos from their parent star, bringing them close enough to be tidally disrupted. We investigate the chance of planet tidal captures by running three-body encounters of SMBH-star-planet systems with a high-accuracy regularized code. We show that tidally captured planets have orbits close to those of their parent star. We conclude that the final periapsis distance of the captured planet from the SMBH will be much larger than 200 AU, unless its parent star was already on a highly eccentric orbit.

  9. Geometric properties of hydraulic-relevant tidal bedforms

    DEFF Research Database (Denmark)

    Winter, Christian; Ferret, Yann; Lefebvre, Alice

    2013-01-01

    on the tidal stage: Whereas the secondary bedforms act as roughness elements throughout the tidal cycle, the large primary bedforms dominate the hydraulics when the tidal flow is in the (dominant) direction of the bedform orientation (e.g. ebb-directed primary bedforms act during ebb currents) when...... slope of 10° or more; which is considered as a threshold condition for the development of flow separation and recirculation eddies in the bedform lee. Only 4.2% of all identified bedforms meet this criterion (n=1,250). These scale with H=0.1923L0.6311 (R²=0.92) when taking into account weighted bedform...

  10. A Gravitational-Tidal Mechanism for the Earth's Polar Oscillations

    Science.gov (United States)

    Akulenko, L. D.; Kumakshev, S. A.; Markov, Yu. G.; Rykhlova, L. V.

    2005-10-01

    Perturbed, rotational-oscillational motions of the Earth induced by the gravitational torques exerted by the Sun and Moon are studied using a linear mechanical model for a viscoelastic rigid body. A tidal mechanism is identified for the excitation of polar oscillations, i.e., for oscillations of the angular-velocity vector specified in a fixed coordinate frame, attributed to the rotational-progressive motion of the barycenter of the Earth-Moon “binary planet” about the Sun. The main features of the oscillations remain stable and do not change considerably over time intervals significantly exceeding the precessional period of the Earth’s axis. A simple mathematical model containing two frequencies, namely, the Chandler and annual frequencies, is constructed using the methods of celestial mechanics. This model is adequate to the astrometric measurements performed by the International Earth Rotation Service (IERS). The parameters of the model are identified via least-squares fitting and a spectral analysis of the IERS data. Statistically valid interpolations of the data for time intervals covering from several months to 15 20 yr are obtained. High-accuracy forecasting of the polar motions for 0.5 1 yr and reasonably trustworthy forecasting for 1 3 yr demonstrated by observations over the last few years are presented for the first time. The results obtained are of theoretical interest for dynamical astronomy, geodynamics, and celestial mechanics, and are also important for astrometrical, navigational, and geophysical applications.

  11. Tidal origin of spiral arms in galaxies orbiting a cluster

    CERN Document Server

    Semczuk, Marcin; del Pino, Andres

    2016-01-01

    One of the scenarios for the formation of grand-design spiral arms in disky galaxies involves their interactions with a satellite or another galaxy. Here we consider another possibility, where the perturbation is instead due to the potential of a galaxy cluster. Using $N$-body simulations we investigate the formation and evolution of spiral arms in a Milky Way-like galaxy orbiting a Virgo-like cluster. The galaxy is placed on a few orbits of different size but similar eccentricity and its evolution is followed for 10 Gyr. The tidally induced, two-armed, approximately logarithmic spiral structure forms on each of them during the pericenter passages. The spiral arms dissipate and wind up with time, to be triggered again at the next pericenter passage. We confirm this transient and recurrent nature of the arms by analyzing the time evolution of the pitch angle and the arm strength. We find that the strongest arms are formed on the tightest orbit, however they wind up rather quickly and are disturbed by another p...

  12. Analysis of Tidal Data for Dagang Tidal Gauge and Study of the Changes for the National Height Datum

    Directory of Open Access Journals (Sweden)

    WU Fumei

    2015-07-01

    Full Text Available The main tides affecting Dagang sea level are analyzed and the national height datum is studied by analyzing 1980—2011 hourly tidal data and 1952—2007 monthly mean tidal data. Firstly, the frequencies and amplitudes of main tides including 180 short-period tides and 6 long-period tides are gained by the Fouirer transform. Then the actual amplitudes and their variations of main tides are obtained by the harmonic analysis of the 1980—2011 hourly tidal data, and the changes with about 19 year period can easily be found in the amplitudes of Q1、O1、M2、K1、K2. And then the changes of the mean sea level at Dagang tidal gauge defining national height datum during the period of 1952—2011 are studied by the harmonic analysis and the shifting average of 18.61 year tidal heights. The results of these methods show that the mean sea level at Dagang tidal gauge descended with the speed of 1.07 mm/a and 0.76 mm/a respectively during 1952—1980, and that it ascended with the speed of 1.59 mm/a and 1.62 mm/a respectively during 1980—2011. And finally the difference of 0.14 cm is achieved by the shifting average of 18.61 year tidal heights for 1985 National Height Datum.

  13. The importance of being coupled: Stable states and catastrophic shifts in tidal biomorphodynamics

    Science.gov (United States)

    Marani, Marco; D'Alpaos, Andrea; Lanzoni, Stefano; Carniello, Luca; Rinaldo, Andrea

    2010-10-01

    We describe and apply a point model of the joint evolution of tidal landforms and biota which incorporates the dynamics of intertidal vegetation; benthic microbial assemblages; erosional, depositional, and sediment exchange processes; wind-wave dynamics, and relative sea level change. Alternative stable states and punctuated equilibria emerge, characterized by possible sudden transitions of the system state, governed by vegetation type, disturbances of the benthic biofilm, sediment availability, and marine transgressions or regressions. Multiple stable states are suggested to result from the interplay of erosion, deposition, and biostabilization, providing a simple explanation for the ubiquitous presence of the typical landforms observed in tidal environments worldwide. The main properties of accessible equilibrium states prove robust with respect to specific modeling assumptions and are thus identified as characteristic dynamical features of tidal systems. Halophytic vegetation emerges as a key stabilizing factor through wave dissipation, rather than a major trapping agent, because the total inorganic deposition flux is found to be largely independent of standing biomass under common supply-limited conditions. The organic sediment production associated with halophytic vegetation represents a major contributor to the overall deposition flux, thus critically affecting the ability of salt marshes to keep up with high rates of relative sea level rise. The type and number of available equilibria and the possible shifts among them are jointly driven and controlled by the available suspended sediment, the rate of relative sea level change, and vegetation and microphytobenthos colonization. The explicit description of biotic and abiotic processes thus emerges as a key requirement for realistic and predictive models of the evolution of a tidal system as a whole. The analysis of such coupled processes finally indicates that hysteretic switches between stable states arise

  14. Tidal deformability and I-Love-Q relations for gravastars with polytropic thin shells

    Science.gov (United States)

    Uchikata, Nami; Yoshida, Shijun; Pani, Paolo

    2016-09-01

    The moment of inertia, the spin-induced quadrupole moment, and the tidal Love number of neutron-star and quark-star models are related through some relations which depend only mildly on the stellar equation of state. These "I-Love-Q" relations have important implications for astrophysics and gravitational-wave astronomy. An interesting problem is whether similar relations hold for other compact objects and how they approach the black hole limit. To answer these questions, here we investigate the deformation properties of a large class of thin-shell gravastars, which are exotic compact objects that do not possess an event horizon nor a spacetime singularity. Working in a small-spin and small-tidal field expansion, we calculate the moment of inertia, the quadrupole moment, and the (quadrupolar electric) tidal Love number of gravastars with a polytropic thin shell. The I-Love-Q relations of a thin-shell gravastar are drastically different from those of an ordinary neutron star. The Love number and quadrupole moment for less compact models have the opposite sign relative to those of ordinary neutron stars, and the I-Love-Q relations continuously approach the black hole limit. We consider a variety of polytropic equations of state for the matter shell and find no universality in the I-Love-Q relations. However, we cannot deny the possibility that, similarly to the neutron-star case, an approximate universality might emerge for a limited class of equations of state. Finally, we discuss how a measurement of the tidal deformability from the gravitational-wave detection of a compact-binary inspiral can be used to constrain exotic compact objects like gravastars.

  15. Development of a Multi-Site and Multi-Device Webgis-Based Tool for Tidal Current Energy Development

    Science.gov (United States)

    Ang, M. R. C. O.; Panganiban, I. K.; Mamador, C. C.; De Luna, O. D. G.; Bausas, M. D.; Cruz, J. P.

    2016-06-01

    A multi-site, multi-device and multi-criteria decision support tool designed to support the development of tidal current energy in the Philippines was developed. Its platform is based on Geographic Information Systems (GIS) which allows for the collection, storage, processing, analyses and display of geospatial data. Combining GIS tools with open source web development applications, it becomes a webGIS-based marine spatial planning tool. To date, the webGIS-based tool displays output maps and graphs of power and energy density, site suitability and site-device analysis. It enables stakeholders and the public easy access to the results of tidal current energy resource assessments and site suitability analyses. Results of the initial development showed that it is a promising decision support tool for ocean renewable energy project developments.

  16. Impacts of salt marsh plants on tidal channel initiation and inheritance

    Science.gov (United States)

    Schwarz, C.; Ye, Q. H.; Wal, D.; Zhang, L. Q.; Bouma, T.; Ysebaert, T.; Herman, P. M. J.

    2014-02-01

    At the transition between mudflat and salt marsh, vegetation is traditionally regarded as a sustaining factor for previously incised mudflat channels, able to conserve the channel network via bank stabilization following plant colonization (i.e., vegetation-stabilized channel inheritance). This is in contrast to recent studies revealing vegetation as the main driver of tidal channel emergence through vegetation-induced channel erosion. We present a coupled hydrodynamic morphodynamic plant growth model to simulate plant expansion and channel formation by our model species (Spartina alterniflora) during a mudflat-salt marsh transition with various initial bathymetries (flat, shoal dense, shoal sparse, and deep dense channels). This simulated landscape development is then compared to remote sensing images of the Yangtze estuary, China, and the Scheldt estuary in Netherlands. Our results propose the existence of a threshold in preexisting mudflat channel depth, which favors either vegetation-stabilized channel inheritance or vegetation-induced channel erosion processes. The increase in depth of preexisting mudflat channels favors flow routing through them, consequently leaving less flow and momentum remaining for vegetation-induced channel erosion processes. This threshold channel depth will be influenced by field specific parameters such as hydrodynamics (tidal range and flow), sediment characteristics, and plant species. Hence, our study shows that the balance between vegetation-stabilized channel inheritance and vegetation-induced channel erosion depends on ecosystem properties.

  17. Logistic Regression Analyses for Predicting Clinically Important Differences in Motor Capacity, Motor Performance, and Functional Independence after Constraint-Induced Therapy in Children with Cerebral Palsy

    Science.gov (United States)

    Wang, Tien-ni; Wu, Ching-yi; Chen, Chia-ling; Shieh, Jeng-yi; Lu, Lu; Lin, Keh-chung

    2013-01-01

    Given the growing evidence for the effects of constraint-induced therapy (CIT) in children with cerebral palsy (CP), there is a need for investigating the characteristics of potential participants who may benefit most from this intervention. This study aimed to establish predictive models for the effects of pediatric CIT on motor and functional…

  18. Field Observations and Model Predictions of Wave Transformation, Setup, Runup, and Turbulence on a Macro-tidal Beach, Korea

    Science.gov (United States)

    Yoo, J.; Shin, S.; Jun, K.; Shim, J.

    2011-12-01

    Surf-zone wave dynamics are one of important driving forces in coastal morphology by inducing beach erosions and sediment transports in inter-tidal shallow water areas, due to active wave breaking, energetic turbulence and violent near-bed velocities. Morphological beach changes are also considerably associated with other surf-zone hydro-dynamics such as nearshore wave transformation, water levels, wave run-up, set-up and coastal currents. In earlier studies, the COBRAS model (a RANS model, developed by Lin and Liu of Cornell University) has been used to investigate such beach processes with reasonable success, mostly, in wave dominant micro-tidal environments. The model solves the RANS equations using VOF method and k-epsilon closure scheme. Recently, intensive field experiments were carried out at a macro-tide environment (i.e. the Mallipo sand beach located in the west coast of Korea, having a large inter-tidal range of 7 m to investigate the complicated surf zone hydro-dynamics under interactions of coastal waves, strong tidal currents, and nearshore bathymetries. The field observation data are used to evaluate the capability of the RANS model to predict the cross-shore variations of free surface, wave set-up, wave run-up, and velocities on the Mallipo Beach. Since the dataset of water surface elevations includes both waves and tides, the COBRAS model was tried to simulate waves accompanied with tidal currents. The measured water surface elevation data were divided into wave and tidal components, in order to be used as inputs of the model. Comparisons of the measurements and the predictions show (1) performance of the model for the wave transformation, wave set-up, and wave run-up on the macro-tidal beach, (2) predictive capability for the turbulence closure scheme in the surf and swash zones, and (3) overall skills to predict under-tows and tidal currents. Acknowledgement This work was supported by the KORDI (Grant PE98572, PE98573 and PM56300). This work was

  19. Effect of Doubly Fed Induction GeneratorTidal Current Turbines on Stability of a Distribution Grid under Unbalanced Voltage Conditions

    Directory of Open Access Journals (Sweden)

    Dahai Zhang

    2017-02-01

    Full Text Available This paper analyses the effects of doubly fed induction generator (DFIG tidal current turbines on a distribution grid under unbalanced voltage conditions of the grid. A dynamic model of an electrical power system under the unbalanced network is described in the paper, aiming to compare the system performance when connected with and without DFIG at the same location in a distribution grid. Extensive simulations of investigating the effect of DFIG tidal current turbine on stability of the distribution grid are performed, taking into account factors such as the power rating, the connection distance of the turbine and the grid voltage dip. The dynamic responses of the distribution system are examined, especially its ability to ride through fault events under unbalanced grid voltage conditions. The research has shown that DFIG tidal current turbines can provide a good damping performance and that modern DFIG tidal current power plants, equipped with power electronics and low-voltage ride-through capability, can stay connected to weak electrical grids even under the unbalanced voltage conditions, whilst not reducing system stability.

  20. Feeding ecology of Liza spp. in a tidal flat: Evidence of the importance of primary production (biofilm) and associated meiofauna

    Science.gov (United States)

    Carpentier, Alexandre; Como, Serena; Dupuy, Christine; Lefrançois, Christel; Feunteun, Eric

    2014-09-01

    Grey mullets are unique among temperate-region fish species in their ability to feed on mudflat biofilm. In this study, we examined mullet feeding strategies on biofilm and associated meiofauna by using a diet study and stable isotope analysis to explore functional interactions between mullets and tidal flats. A stomach vacuity investigation showed that mullets did not import any materials from subtidal areas into the mudflat but exported mud, biofilm, and associated meiofauna. The results of mullet stomach content and fecal analyses, when compared to the availability of tidal flat resources, showed evidence of mullets' ability to ingest and assimilate biofilm and to concentrate major meiofauna grazers such as nematodes, copepods and, secondarily, foraminifers and ostracods. Isotopic ratios confirmed diet investigations, and as recently shown in salt marsh habitats, mullets exhibited an intermediate trophic position, supporting the hypothesis that they can assimilate both biofilm and major meiofauna grazers. The function of the tidal flat as a feeding habitat for gray mullets and the role of mullets as the main export pathway of biofilm from tidal flat ecosystems are discussed.

  1. Inundation Mapping Tidal Surface - Mean Higher High Water

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are a derived product of the NOAA VDatum tool and they extend the tool's Mean Higher High Water (MHHW) tidal datum conversion inland beyond its original...

  2. Optimal Selection of Floating Platform for Tidal Current Power Station

    Directory of Open Access Journals (Sweden)

    Fengmei Jing

    2013-06-01

    Full Text Available With continuous development of marine engineering, more and more new structures are used in the exploring of tidal current energy. Three are there different kinds of support structures for tidal current power station, which are sea-bed mounted/gravity based system, pile mounted system and floating moored platform. Comparison with them, the floating mooring system is suit for deep water and the application of which will be widely. In this study, catamaran and semi-submersible as floating platform of tidal current power station are studied. And they are compared with its economic, efficiency of turbine and stability of station. It is found that the catamaran is optimal choice. Based on basic ship theory and using software MOSES, the stability of Catamaran tidal current power station is also calculated. The research of this study is significant and it will be as the reference for the future study.

  3. Turbine Control of a Tidal and River Power Generator

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard; Wright, Alan; Gevorgian, Vahan; Donegan, James; Marnagh, Cian; McEntee, Jarlath

    2016-11-21

    As renewable generation has become less expensive during recent decades, and it becomes more accepted by the global population, the focus on renewable generation has expanded to include new types with promising future applications, such as river and tidal generation. The input variations to these types of resources are slower but also steadier than wind or solar generation. The level of water turbulent flow may vary from one place to another, however, the control algorithm can be adjusted to local environment. This paper describes the hydrokinetic aspects of river and tidal generation based on a river and tidal generator. Although the information given in this paper is not that of an exact generator deployed on site, the data used is representative of a typical river or tidal generator. In this paper, the hydrokinetic and associated electrical controller of the system were not included; however, the focus of this paper is on the hydrodynamic control.

  4. Experimental hydrodynamic study of the Qiantang River tidal bore

    Institute of Scientific and Technical Information of China (English)

    HUANG Jing; PAN Cun-hong; KUANG Cui-ping; ZENG Jian; CHEN Gang

    2013-01-01

    To study the hydrodynamics of tidal bore,a physical modeling study is carried out in a rectangular flume with considerations of the tidal bore heights,the propagation speeds,the tidal current velocities,the front steepness,and the bore shapes.After the validation with the field observations,the experimental results are analyzed,and it is shown that:(1) the greater initial ebb velocity or the larger initial water depth impedes the tidal bore propagation,(2) the maximum bore height appears at an initial ebb velocity in the range of 0.5 m/s-1.5 m/s,(3) when the Froude number exceeds 1.2,an undular bore appears,after it exceeds 1.3,a breaking bore occurs,and after it exceeds 1.7,the bore is broken.

  5. Tidal Love numbers of membrane worlds: Europa, Titan, and Co

    CERN Document Server

    Beuthe, Mikael

    2015-01-01

    Under tidal forcing, icy satellites with subsurface oceans deform as if the surface were a membrane stretched around a fluid layer. `Membrane worlds' is thus a fitting name for these bodies and membrane theory provides the perfect toolbox to predict tidal effects. I describe here a new membrane approach to tidal perturbations based on the general theory of viscoelastic-gravitational deformations of spherically symmetric bodies. The massive membrane approach leads to explicit formulas for viscoelastic tidal Love numbers which are exact in the limit of zero crust thickness. The accuracy on $k_2$ and $h_2$ is better than one percent if the crust thickness is less than five percents of the surface radius, which is probably the case for Europa and Titan. The new approach allows for density differences between crust and ocean and correctly includes crust compressibility. This last feature makes it more accurate than the propagation matrix method. Membrane formulas factorize shallow and deep interior contributions, ...

  6. Turbine Control of a Tidal and River Power Generator: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard; Gevorgian, Vahan; Wright, Alan; Donegan, James; Marnagh, Cian; McEntee, Jarlath

    2016-08-01

    As renewable generation has become less expensive during recent decades, and it becomes more accepted by the global population, the focus on renewable generation has expanded to include new types with promising future applications, such as river and tidal generation. The input variations to these types of resources are slower but also steadier than wind or solar generation. The level of water turbulent flow may vary from one place to another, however, the control algorithm can be adjusted to local environment. This paper describes the hydrokinetic aspects of river and tidal generation based on a river and tidal generator. Although the information given in this paper is not that of an exact generator deployed on site, the data used is representative of a typical river or tidal generator. In this paper, the hydrokinetic and associated electrical controller of the system were not included; however, the focus of this paper is on the hydrodynamic control.

  7. The application of Yangtze Estuary Tidal Wetlands Geographic Information System

    Institute of Scientific and Technical Information of China (English)

    WANGJun; CHENZhenlou; XUShiyuan; WANGDongqi; LIUJie

    2005-01-01

    Yangtze Estuary Tidal Wetlands Geographic Information System (YETWGIS) is a comprehensive software system for environmental management and decision of Yangtze estuary tidal wetlands. Based on MapObjects components technology, Data Mining technology, mathematical modeling method and Visual Basic language, this software system has many functions such as displaying, editing, querying and searching, spatial statistics and analysis, thematic map compiling, and environmental quality evaluation. This paper firstly outlined the system structure, key techniques, and achieving methods of YETWGIS, and then, described the core modules (the thematic map compiling module and environmental quality evaluation model module) in detail. In addition, based on information entropy model, it thoroughly discussed the methods of environmental quality evaluation and indicators' weight calculation. Finally, by using YETWGIS, this paper analyzed the spatial distribution characteristics of Heavy Metal and Persistent Organic Pollutants (POPs) of the Yangtze estuary tidal wetlands in 2002, and evaluated the environmental quality of the Yangtze estuary tidal wetlands in 2003.

  8. Department of Energy's team's analyses of Soviet designed VVERs

    Energy Technology Data Exchange (ETDEWEB)

    1989-09-01

    This document provides Appendices A thru K of this report. The topics discussed respectively are: radiation induced embrittlement and annealing of reactor pressure vessel steels; loss of coolant accident blowdown analyses; LOCA blowdown response analyses; non-seismic structural response analyses; seismic analyses; S'' seal integrity; reactor transient analyses; fire protection; aircraft impacts; and boric acid induced corrosion. (FI).

  9. Modeling the Ocean Tide for Tidal Power Generation Applications

    Science.gov (United States)

    Kawase, M.; Gedney, M.

    2014-12-01

    Recent years have seen renewed interest in the ocean tide as a source of energy for electrical power generation. Unlike in the 1960s, when the tidal barrage was the predominant method of power extraction considered and implemented, the current methodology favors operation of a free-stream turbine or an array of them in strong tidal currents. As tidal power generation moves from pilot-scale projects to actual array implementations, numerical modeling of tidal currents is expected to play an increasing role in site selection, resource assessment, array design, and environmental impact assessment. In this presentation, a simple, coupled ocean/estuary model designed for research into fundamental aspects of tidal power generation is described. The model consists of a Pacific Ocean-size rectangular basin and a connected fjord-like embayment with dimensions similar to that of Puget Sound, Washington, one of the potential power generation sites in the United States. The model is forced by an idealized lunar tide-generating potential. The study focuses on the energetics of a tidal system including tidal power extraction at both global and regional scales. The hyperbolic nature of the governing shallow water equations means consequence of tidal power extraction cannot be limited to the local waters, but is global in extent. Modeling power extraction with a regional model with standard boundary conditions introduces uncertainties of 3 ~ 25% in the power extraction estimate depending on the level of extraction. Power extraction in the model has a well-defined maximum (~800 MW in a standard case) that is in agreement with previous theoretical studies. Natural energy dissipation and tidal power extraction strongly interact; for a turbine array of a given capacity, the higher the level of natural dissipation the lower the power the array can extract. Conversely, power extraction leads to a decrease in the level of natural dissipation (Figure) as well as the tidal range and the

  10. Effects of vegetation patterns and grazers on tidal marshes

    OpenAIRE

    Elschot, K.

    2015-01-01

    SUMMARYsoil. These effects of large-bodied grazers on soil properties in tidal marshes has beenlargely neglected so far, but need to be considered when we want to introduce livestockto ungrazed marshes.Next to above-ground grazing, we also find small grazers that grub for below-groundstorage organs in tidal marshes. This type of grazing removes the entire plant and it istherefore much more difficult for the vegetation to regenerate. This grubbing behaviorgenerally causes bare patches to form ...

  11. Tidal resource extraction in the Pentland Firth, UK

    OpenAIRE

    2015-01-01

    Large-scale extraction of power from tidal streams within the Pentland Firth is expected to be underway in the near future. The Inner Sound of Stroma in particular has attracted significant commercial interest. To understand potential environmental impacts of the installation of a tidal turbine array a case study based upon the Inner Sound is considered. A numerical computational fluid dynamics model, Fluidity, is used to conduct a series of depth-averaged simulations to investigate velocity ...

  12. On the superposition of bedforms in a tidal channel

    DEFF Research Database (Denmark)

    Winter, C; Vittori, G.; Ernstsen, V.B.;

    2008-01-01

    High resolution bathymetric measurements reveal the super-imposition of bedforms in the Grådyb tidal inlet in the Danish Wadden Sea. Preliminary results of numerical model simulations are discussed: A linear stability model was tested to explain the large bedforms as being caused by tidal system...... instabilities. Results show comparable dimensions and migration rates. A three-dimensional morphodynamic model is shown to reproduce small scale transport rates but lacks realistic trends of morphodynamic evolution....

  13. A Tale of Tidal Tails in the Milky Way

    CERN Document Server

    Casey, Andrew R

    2014-01-01

    Hundreds of globular clusters and dwarf galaxies encircle the Milky Way. Many of these systems have undergone partial disruption due to tidal forces, littering the halo with stellar streams. These tidal tails are sensitive to the Galactic potential, facilitating an excellent laboratory to investigate Galaxy formation and evolution, as well as local chemical signatures of differing star formation environments. To better understand the emergence of the Milky Way, this thesis examines the dynamics and chemistry of a number of known stellar streams.

  14. Optimal Design of Tidal Power Generator Using Stochastic Optimization Techniques

    OpenAIRE

    2014-01-01

    Particle Swarm Optimization (PSO) and Genetic Algorithms (GA) are usedto reduce the cost of a permanent magnet synchronous generator with concentratedwindings for tidal power applications. Reducing the cost of the electricalmachine is one way of making tidal energy more competitive compared to traditionalsources of electricity.Hybrid optimization combining PSO or GA with gradient based algorithmsseems to be suited for design of electrical machines. Results from optimizationwith Matlab indicat...

  15. Tidal Marsh Vegetation of China Camp, San Pablo Bay, California

    OpenAIRE

    Baye, Peter R.

    2012-01-01

    China Camp (Marin County, California) preserves extensive relict stands of salt marsh vegetation developed on a prehistoric salt marsh platform with a complex sinuous tidal creek network. The low salt marsh along tidal creeks supports extensive native stands of Pacific cordgrass (Spartina foliosa). The outer salt marsh accreted following hydraulic gold mining sedimentation. It consists of a wave-scarped pickleweed-dominated (Sarcocornia pacifica) high salt marsh terrace with a broad fringing ...

  16. Validation of Numerical Shallow Water Models for Tidal Lagoons

    Energy Technology Data Exchange (ETDEWEB)

    Eliason, D.; Bourgeois, A.

    1999-11-01

    An analytical solution is presented for the case of a stratified, tidally forced lagoon. This solution, especially its energetics, is useful for the validation of numerical shallow water models under stratified, tidally forced conditions. The utility of the analytical solution for validation is demonstrated for a simple finite difference numerical model. A comparison is presented of the energetics of the numerical and analytical solutions in terms of the convergence of model results to the analytical solution with increasing spatial and temporal resolution.

  17. Approximate universal relations among tidal parameters for neutron star binaries

    Science.gov (United States)

    Yagi, Kent; Yunes, Nicolás

    2017-01-01

    One of largest uncertainties in nuclear physics is the relation between the pressure and density of supranuclear matter: the equation of state. Some of this uncertainty may be removed through future gravitational wave observations of neutron star binaries by extracting the tidal deformabilities (or Love numbers) of neutron stars, a novel way to probe nuclear physics in the high-density regime. Previous studies have shown that only a certain combination of the individual (quadrupolar) deformabilities of each body (the so-called chirp tidal deformability) can be measured with second-generation, gravitational wave interferometers, such as Adv. LIGO, due to correlations between the individual deformabilities. To overcome this, we search for approximately universal (i.e. approximately equation-of-state independent) relations between two combinations of the individual tidal deformabilities, such that once one of them has been measured, the other can be automatically obtained and the individual ones decoupled through these relations. We find an approximately universal relation between the symmetric and the anti-symmetric combination of the individual tidal deformabilities that is equation-of-state-insensitive to 20 % for binaries with masses less than 1.7{{M}⊙} . We show that these relations can be used to eliminate a combination of the tidal parameters from the list of model parameters, thus breaking degeneracies and improving the accuracy in parameter estimation. A simple (Fisher) study shows that the universal binary Love relations can improve the accuracy in the extraction of the symmetric combination of tidal parameters by as much as an order of magnitude, making the overall accuracy in the extraction of this parameter slightly better than that of the chirp tidal deformability. These new universal relations and the improved measurement accuracy on tidal parameters not only are important to astrophysics and nuclear physics, but also impact our ability to probe

  18. Secular tidal changes in lunar orbit and Earth rotation

    Science.gov (United States)

    Williams, James G.; Boggs, Dale H.

    2016-11-01

    Small tidal forces in the Earth-Moon system cause detectable changes in the orbit. Tidal energy dissipation causes secular rates in the lunar mean motion n, semimajor axis a, and eccentricity e. Terrestrial dissipation causes most of the tidal change in n and a, but lunar dissipation decreases eccentricity rate. Terrestrial tidal dissipation also slows the rotation of the Earth and increases obliquity. A tidal acceleration model is used for integration of the lunar orbit. Analysis of lunar laser ranging (LLR) data provides two or three terrestrial and two lunar dissipation parameters. Additional parameters come from geophysical knowledge of terrestrial tides. When those parameters are converted to secular rates for orbit elements, one obtains d n/d t = -25.97± 0.05 ''/cent2, d a/d t = 38.30 ± 0.08 mm/year, and d i/d t = -0.5 ± 0.1 μas/year. Solving for two terrestrial time delays and an extra d e/d t from unspecified causes gives ˜ 3× 10^{-12}/year for the latter; solving for three LLR tidal time delays without the extra d e/d t gives a larger phase lag of the N2 tide so that total d e/d t = (1.50 ± 0.10)× 10^{-11}/year. For total d n/d t, there is ≤ 1 % difference between geophysical models of average tidal dissipation in oceans and solid Earth and LLR results, and most of that difference comes from diurnal tides. The geophysical model predicts that tidal deceleration of Earth rotation is -1316 ''/cent2 or 87.5 s/cent2 for UT1-AT, a 2.395 ms/cent increase in the length of day, and an obliquity rate of 9 μas/year. For evolution during past times of slow recession, the eccentricity rate can be negative.

  19. Small RNA sequencing-microarray analyses in Parkinson leukocytes reveal deep brain stimulation-induced and splicing changes that classify brain region transcriptomes

    Directory of Open Access Journals (Sweden)

    Lilach eSoreq

    2013-05-01

    Full Text Available MicroRNAs (miRNAs are key post transcriptional regulators of their multiple target genes. However, the detailed profile of miRNA expression in Parkinson's disease, the second most common neurodegenerative disease worldwide and the first motor disorder has not been charted yet. Here, we report comprehensive miRNA profiling by next-generation small-RNA sequencing, combined with targets inspection by splice-junction and exon arrays interrogating leukocyte RNA in Parkinson’s disease patients before and after deep brain stimulation (DBS treatment and of matched healthy control volunteers (HC. RNA-Seq analysis identified 254 miRNAs and 79 passenger strand forms as expressed in blood leukocytes, 16 of which were modified in patients pre treatment as compared to HC. 11 miRNAs were modified following brain stimulation, 5 of which were changed inversely to the disease induced changes. Stimulation cessation further induced changes in 11 miRNAs. Transcript isoform abundance analysis yielded 332 changed isoforms in patients compared to HC, which classified brain transcriptomes of 47 PD and control independent microarrays. Functional enrichment analysis highlighted mitochondrion organization. DBS induced 155 splice changes, enriched in ubiquitin homeostasis. Cellular composition analysis revealed immune cell activity pre and post treatment. Overall, 217 disease and 74 treatment alternative isoforms were predictably targeted by modified miRNAs within both 3’ and 5’ untranslated ends and coding sequence sites. The stimulation-induced network sustained 4 miRNAs and 7 transcripts of the disease network. We believe that the presented dynamic networks provide a novel avenue for identifying disease and treatment-related therapeutic targets. Furthermore, the identification of these networks is a major step forward in the road for understanding the molecular basis for neurological and neurodegenerative diseases and assessment of the impact of brain stimulation

  20. Metabolomic Analyses of Brain Tissue in Sepsis Induced by Cecal Ligation Reveal Specific Redox Alterations--Protective Effects of the Oxygen Radical Scavenger Edaravone.

    Science.gov (United States)

    Hara, Naomi; Chijiiwa, Miyuki; Yara, Miki; Ishida, Yusuke; Ogiwara, Yukihiko; Inazu, Masato; Kuroda, Masahiko; Karlsson, Michael; Sjovall, Fredrik; Elmér, Eskil; Uchino, Hiroyuki

    2015-12-01

    The pathophysiology of sepsis-associated encephalopathy (SAE) is complex and remains incompletely elucidated. Dysregulated reactive oxygen species (ROS) production and mitochondrial-mediated necrotic-apoptotic pathway have been proposed as part of the pathogenesis. The present study aimed at analyzing the preventive effect of the free radical scavenger edaravone on sepsis-induced brain alterations. Sepsis was induced by cecal ligation and puncture (CLP) and the mice were divided into three groups-CLP vehicle (CLPV), CLP and edaravone (MCI-186, 3-methyl-1-phenyl-2-pyrazolin-5-one) (CLPE), and sham-operated (Sham). Mice in CLPV and CLPE were injected with saline or edaravone intraperitoneally at a dose of 10 mg/kg twice daily. The treatments were initiated 4 days prior to the surgical procedure. Mortality, histological changes, electron microscopy (EM), and expression of Bcl-2 family genes (Bcl-2 and Bax) were analyzed in selected brain regions. CLPE showed significant improvement in survival compared with CLPV 18 h postinduction of sepsis (P free radical scavenger edavarone reduces mortality of septic mice and protects against sepsis-induced neuronal cell death.

  1. Tidal disruption rate of stars by spinning supermassive black holes

    CERN Document Server

    Kesden, Michael

    2011-01-01

    A supermassive black hole can disrupt a star when its tidal field exceeds the star's self-gravity, and can directly capture stars that cross its event horizon. For black holes with mass M > 10^7 solar masses, tidal disruption of main-sequence stars occurs close enough to the event horizon that a Newtonian treatment of the tidal field is no longer valid. The fraction of stars that are directly captured is also no longer negligible. We calculate generically oriented stellar orbits in the Kerr metric, and evaluate the relativistic tidal tensor at pericenter for those stars not directly captured by the black hole. We combine this relativistic analysis with previous calculations of how these orbits are populated to determine tidal-disruption rates for spinning black holes. We find, consistent with previous results, that black-hole spin increases the upper limit on the mass of a black hole capable of tidally disrupting solar-like stars to ~7 x 10^8 solar masses. More quantitatively, we find that direct stellar capt...

  2. The Conceptual Design of a Tidal Power Plant in Taiwan

    Directory of Open Access Journals (Sweden)

    Jia-Shiuan Tsai

    2014-06-01

    Full Text Available Located on the northwestern of Taiwan, the Matsu archipelago is near mainland China and comprises four islands: Nangan, Beigan, Juguang, and Dongyin. The population of Matsu totals 11,196 and is chiefly concentrated on Nangan and Beigan. From 1971 to 2000, Matsu built five oil-fired power plants with a total installed capacity of 47 MW. However, the emissions and noise generated by the oil-fired power plant has caused damage to Matsu’s environment, and the cost of fuel is high due to the long-distance shipping from Taiwan. Developing renewable energy in Matsu has therefore been a fervent topic for the Taiwan government, and tidal power is considered to be of the highest priority due to Matsu’s large tidal range (4.29 m in average and its semidiurnal tide. Moreover, the islands of Nangan and Beigan are composed of granite and have natural harbors, rendering them ideal places for coastal engineering of tidal power plants. This paper begins with a renewable energy reserves assessment in Matsu to determine the amount of tidal energy. Next, a tidal turbine type of the lowest cost is chosen, and then its dynamic characteristic, performance, and related design are analyzed. Finally, the coastal engineering condition was investigated, and a conceptual design for tidal power plant is proposed.

  3. Merging Galaxies with Tidal Tails in COSMOS to z=1

    CERN Document Server

    Wen, Z Z

    2016-01-01

    Tidal tails are created in major mergers involving disk galaxies. How the tidal tails trace the assembly history of massive galaxies remains to be explored. We identify a sample of 461 merging galaxies with long tidal tails from 35076 galaxies mass-complete at $M_\\star\\ge 10^{9.5}\\,M_{\\odot}$ and $0.2\\leq z\\leq1$ based on HST/ACS F814W imaging data and public catalogs of the COSMOS field. The long tails refer to these with length equal to or longer than the diameter of their host galaxies. The mergers with tidal tails are selected using our novel $A_{\\rm O}-D_{\\rm O}$ technique for strong asymmetric features together with visual examination. Our results show that the fraction of tidal-tailed mergers evolves mildly with redshift, as $\\sim (1+z)^{2.0\\pm0.4}$, and becomes relatively higher in less massive galaxies out to $z=1$. With a timescale of 0.5 Gyr for the tidal-tailed mergers, we obtain that the occurrence rate of such mergers follows $0.01\\pm 0.007\\,(1+z)^{2.3\\pm 1.4}$ Gyr$^{-1}$ and corresponds to $\\si...

  4. Geographic variation in Puget Sound tidal channel planform geometry

    Science.gov (United States)

    Hood, W. Gregory

    2015-02-01

    Tidal channels are central elements of salt marsh hydrodynamics, sediment dynamics, and habitat. To develop allometric models predicting the number and size of tidal channels that could develop following salt marsh restoration, channels were digitized from aerial photographs of Puget Sound river delta marshes. Salt marsh area was the independent variable for all dependent channel planform metrics. Tidal channel allometry showed similar scaling exponents for channel planform metrics throughout Puget Sound, simplifying comparisons between locations. Y-intercepts of allometric relationships showed geographic variation, which multiple-regression indicated was associated with tidal range and storm significant wave height. Channel size and complexity were positively related to tidal range and negatively related to wave height. Four case studies, each with paired regions of similar tidal range and contrasting wave environments, further indicated wave environment affected channel geometry. Wave-mediated sediment delivery may be the mechanism involved, with wave-sheltered areas experiencing relative sediment deficits, such that some salt marshes in Puget Sound are already suffering sea-level rise impacts that are reflected in their channel network geometry.

  5. Tidal dunes versus tidal bars: The sedimentological and architectural characteristics of compound dunes in a tidal seaway, the lower Baronia Sandstone (Lower Eocene), Ager Basin, Spain

    Science.gov (United States)

    Olariu, Cornel; Steel, Ronald J.; Dalrymple, Robert W.; Gingras, Murray K.

    2012-11-01

    The Lower Eocene Baronia Formation in the Ager Basin is interpreted as a series of stacked compound dunes confined within a tectonically generated embayment or tidal seaway. This differs from the previous interpretation of lower Baronia sand bodies as tidal bars in the front of a delta. The key architectural building block of the succession, the deposit of a single compound dune, forms a 1-3 m-thick, upward coarsening succession that begins with highly bioturbated, muddy, very fine to fine grained sandstone that contains an open-marine Cruziana ichnofacies. This is overlain gradationally by ripple-laminated sandstone that is commonly bioturbated and contains mud drapes. The succession is capped by fine- to coarse-grained sandstones that contain both planar and trough cross-strata with unidirectional or bi-directional paleocurrent directions and occasional thin mud drapes on the foresets. The base of a compound dune is gradational where it migrated over muddy sandstone deposited between adjacent dunes, but is sharp and erosional where it migrated over the stoss side of a previous compound dune. The cross strata that formed by simple superimposed dunes dip in the same direction as the inclined master bedding planes within the compound dune, forming a forward-accretion architecture. This configuration is the fundamental reason why these sandbodies are interpreted as compound tidal dunes rather than as tidal bars, which, in contrast, generate lateral-accretion architecture. In the Baronia, fields of compound dunes generated tabular sandbodies 100s to 1000s of meters in extent parallel to the paleocurrent direction and up to 6 m thick that alternate vertically with highly bioturbated muddy sandstones (up to 10 m thick) that represent the low-energy fringes of the dune fields or periods of high sea level when current speeds decreased. Each cross-stratified sandstone sheet (compound-dune complexes) contains overlapping lenticular "shingles" formed by individual compound

  6. Patient-specific simulation of tidal breathing

    Science.gov (United States)

    Walters, M.; Wells, A. K.; Jones, I. P.; Hamill, I. S.; Veeckmans, B.; Vos, W.; Lefevre, C.; Fetitia, C.

    2016-03-01

    Patient-specific simulation of air flows in lungs is now straightforward using segmented airways trees from CT scans as the basis for Computational Fluid Dynamics (CFD) simulations. These models generally use static geometries, which do not account for the motion of the lungs and its influence on important clinical indicators, such as airway resistance. This paper is concerned with the simulation of tidal breathing, including the dynamic motion of the lungs, and the required analysis workflow. Geometries are based on CT scans obtained at the extremes of the breathing cycle, Total Lung Capacity (TLC) and Functional Residual Capacity (FRC). It describes how topologically consistent geometries are obtained at TLC and FRC, using a `skeleton' of the network of airway branches. From this a 3D computational mesh which morphs between TLC and FRC is generated. CFD results for a number of patient-specific cases, healthy and asthmatic, are presented. Finally their potential use in evaluation of the progress of the disease is discussed, focusing on an important clinical indicator, the airway resistance.

  7. Simultaneous perturbation stochastic approximation for tidal models

    KAUST Repository

    Altaf, M.U.

    2011-05-12

    The Dutch continental shelf model (DCSM) is a shallow sea model of entire continental shelf which is used operationally in the Netherlands to forecast the storm surges in the North Sea. The forecasts are necessary to support the decision of the timely closure of the moveable storm surge barriers to protect the land. In this study, an automated model calibration method, simultaneous perturbation stochastic approximation (SPSA) is implemented for tidal calibration of the DCSM. The method uses objective function evaluations to obtain the gradient approximations. The gradient approximation for the central difference method uses only two objective function evaluation independent of the number of parameters being optimized. The calibration parameter in this study is the model bathymetry. A number of calibration experiments is performed. The effectiveness of the algorithm is evaluated in terms of the accuracy of the final results as well as the computational costs required to produce these results. In doing so, comparison is made with a traditional steepest descent method and also with a newly developed proper orthogonal decompositionbased calibration method. The main findings are: (1) The SPSA method gives comparable results to steepest descent method with little computational cost. (2) The SPSA method with little computational cost can be used to estimate large number of parameters.

  8. A Bright Year for Tidal Disruptions?

    CERN Document Server

    Metzger, Brian D

    2015-01-01

    When a star is tidally disrupted by a supermassive black hole (BH), roughly half of its mass falls back to the BH at super-Eddington rates. Being tenuously gravitationally bound and unable to cool radiatively, only a small fraction f_in few 1e4 K, converting the emission to optical/near-UV wavelengths where photons more readily escape due to the lower opacity. This can explain the unexpectedly low and temporally constant effective temperatures of optically-discovered TDE flares. For BHs with relatively high masses M_BH > 1e7 M_sun the ejecta can become ionized at an earlier stage, or for a wider range of viewing angles, producing a TDE flare which is instead dominated by thermal X-ray emission. We predict total radiated energies consistent with those of observed TDE flares, and ejecta velocities that agree with the measured emission line widths. The peak optical luminosity for M_BH < 1e6 M_sun is suppressed due to adiabatic losses in the inner disk wind, possibly contributing to the unexpected dearth of o...

  9. The tidal disruption of protoplanetary accretion discs

    CERN Document Server

    Larwood, J D

    1997-01-01

    In this paper we revisit the problem of the tidal interaction occuring between a protostellar accretion disc and a secondary point mass following a parabolic trajectory. We model the disc response analytically and we compare our results with three-dimensional SPH simulations. Inviscid as well as viscous hydrodynamics is considered. We show that in a viscous system the response derived from inviscid considerations is predominant even for the highest estimates of an anomalous disc shear viscosity. The angular momentum lost from the disc during the encounter is derived from linear theory, for distant fly-bys, as well as the changes to the disc orientation expected in non-coplanar encounters. It is shown that the target discs can become warped and precess by a small amount during non-coplanar encounters. This small precession is shown to give rise to a relative tilt of the disc which is always more important for determining its final orientation than is the change to the orbital inclination. We discuss the implic...

  10. Stingray tidal stream energy device - phase 3

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    The 150 kW Stingray demonstrator was designed, built and installed by The Engineering Business (EB) in 2002, becoming the world's first full-scale tidal stream generator. The concept and technology are described in the reports from Phases 1 and 2 of the project. This report provides an overview of Phase 3 - the re-installation of Stingray in Yell Sound in the Shetland Isles between July and September 2003 for further testing at slack water and on the flood tide to confirm basic machine characteristics, develop the control strategy and to demonstrate performance and power collection through periods of continuous operation. The overall aim was to demonstrate that electricity could be generated at a potentially commercially viable unit energy cost; cost modelling indicated a future unit energy cost of 6.7 pence/kWh when 100 MW capacity had been installed. The report describes: project objectives, targets and activities; design and production; marine operations including installation and demobilisation; environmental monitoring and impact, including pre-installation and post-decommissioning surveys; stakeholder involvement; test results on machine characteristics, sensor performance, power cycle analysis, power collection, transmission performance and efficiency, current data analysis; validation of the mathematical model; the background to the economic model; cost modelling; and compliance with targets set by the Department of Trade and Industry (DTI).

  11. Abundance Anomalies In Tidal Disruption Events

    CERN Document Server

    Kochanek, C S

    2015-01-01

    The ~10% of tidal disruption events (TDEs) due to stars more massive than the Sun should show abundance anomalies due to stellar evolution in helium, carbon and nitrogen, but not oxygen. Helium is always enhanced, but only by up to ~25% on average because it becomes inaccessible once it is sequestered in the high density core as the star leaves the main sequence. However, portions of the debris associated with the disrupted core of a main sequence star can be enhanced in helium by factors of 2-3 for debris at a common orbital period. These helium abundance variations may be a contributor to the observed diversity of hydrogen and helium line strengths in TDEs. A still more striking anomaly is the rapid enhancement of nitrogen and the depletion of carbon due to the CNO cycle -- stars more massive than the Sun quickly show an increase in their average N/C ratio by factors of 3-10. Because low mass stars evolve slowly and high mass stars are rare, TDEs showing high N/C will almost all be due to 1-2Msun stars disr...

  12. Tidal Love numbers of neutron stars

    CERN Document Server

    Hinderer, Tanja

    2007-01-01

    For a variety of fully relativistic polytropic neutron star models we calculate the star's tidal Love number k2. Most realistic equations of state for neutron stars can be approximated as a polytrope with an effective index n~0.5-1.0. The equilibrium stellar model is obtained by numerical integration of the Tolman-Oppenheimer-Volkhov equations. We calculate the linear l=2 static perturbations to the Schwarzschild spacetime following the method of Thorne and Campolattaro. Combining the perturbed Einstein equations into a single second order differential equation for the perturbation to the metric coefficient g_tt, and matching the exterior solution to the asymptotic expansion of the metric in the star's local asymptotic rest frame gives the Love number. Our results agree well with the Newtonian results in the weak field limit. The fully relativistic values differ from the Newtonian values by up to ~24%. The Love number is potentially measurable in gravitational wave signals from inspiralling binary neutron sta...

  13. The effect of Hurricane Katrina on nekton communities in the tidal freshwater marshes of Breton Sound, Louisiana, USA

    Science.gov (United States)

    Piazza, Bryan P.; La Peyre, Megan K.

    2009-06-01

    Hurricanes are climatically-induced resource pulses that affect community structure through the combination of physical and chemical habitat change. Estuaries are susceptible to hurricane pulses and are thought to be resilient to habitat change, because biotic communities often return quickly to pre-hurricane conditions. Although several examples provide evidence of quick recovery of estuarine nekton communities following a hurricane, few studies take place in tidal freshwater habitat where physical habitat effects can be extensive and may not be readily mitigated. We examined nekton communities (density, biomass, α and β diversity, % occurrence by residence status) in tidal freshwater marshes in Breton Sound, Louisiana, before and after a direct hit by Hurricane Katrina (2005). Vegetative marsh loss in the study area was extensive, and elevated salinity persisted for almost 6 months. Post-Katrina nekton density and biomass increased significantly, and the nekton community shifted from one of tidal freshwater/resident species to one containing brackish/migrant species, many of which are characterized by pelagic and benthic life history strategies. By spring 2007, the nekton community had shifted back to tidal freshwater/resident species, despite the enduring loss of vegetated marsh habitat.

  14. The effect of Hurricane Katrina on nekton communities in the tidal freshwater marshes of Breton Sound, Louisiana, USA

    Science.gov (United States)

    Piazza, Bryan P.; La Peyre, M.K.

    2009-01-01

    Hurricanes are climatically-induced resource pulses that affect community structure through the combination of physical and chemical habitat change. Estuaries are susceptible to hurricane pulses and are thought to be resilient to habitat change, because biotic communities often return quickly to pre-hurricane conditions. Although several examples provide evidence of quick recovery of estuarine nekton communities following a hurricane, few studies take place in tidal freshwater habitat where physical habitat effects can be extensive and may not be readily mitigated. We examined nekton communities (density, biomass, ?? and ?? diversity, % occurrence by residence status) in tidal freshwater marshes in Breton Sound, Louisiana, before and after a direct hit by Hurricane Katrina (2005). Vegetative marsh loss in the study area was extensive, and elevated salinity persisted for almost 6 months. Post-Katrina nekton density and biomass increased significantly, and the nekton community shifted from one of tidal freshwater/resident species to one containing brackish/migrant species, many of which are characterized by pelagic and benthic life history strategies. By spring 2007, the nekton community had shifted back to tidal freshwater/resident species, despite the enduring loss of vegetated marsh habitat. ?? 2009 Elsevier Ltd.

  15. Mercury-T: A new code to study tidally evolving multi-planet systems. Applications to Kepler-62

    CERN Document Server

    Bolmont, Emeline; Leconte, Jeremy; Hersant, Franck; Correia, Alexandre C M

    2015-01-01

    A large proportion of observed planetary systems contain several planets in a compact orbital configuration, and often harbor at least one close-in object. These systems are then most likely tidally evolving. We investigate how the effects of planet-planet interactions influence the tidal evolution of planets. We introduce for that purpose a new open-source addition to the Mercury N-body code, Mercury-T, which takes into account tides, general relativity and the effect of rotation-induced flattening in order to simulate the dynamical and tidal evolution of multi-planet systems. It uses a standard equilibrium tidal model, the constant time lag model. Besides, the evolution of the radius of several host bodies has been implemented (brown dwarfs, M-dwarfs of mass $0.1~M_\\odot$, Sun-like stars, Jupiter). We validate the new code by comparing its output for one-planet systems to the secular equations results. We find that this code does respect the conservation of total angular momentum. We applied this new tool t...

  16. Cold-induced modulation and functional analyses of the DRE-binding transcription factor gene, GmDREB3, in soybean (Glycine max L.)

    OpenAIRE

    Chen, Ming; Xu, Zhaoshi; Xia, Lanqin; Li, Liancheng; Cheng, Xianguo; Dong, Jianhui; Wang, Qiaoyan; Ma, Youzhi

    2008-01-01

    DREB (dehydration-responsive element-binding protein) transcription factors have important roles in the stress-related regulation network in plants. A DREB orthologue, GmDREB3, belonging to the A-5 subgroup of the DREB subfamily, was isolated from soybean using the RACE (rapid amplification of cDNA ends) method. Northern blot analysis showed that expression of GmDREB3 in soybean seedlings was induced following cold stress treatment for 0.5 h and was not detected after 3 h. However, it was not...

  17. Improving the Estimates of International Space Station (ISS) Induced K-Factor Failure Rates for On-Orbit Replacement Unit (ORU) Supportability Analyses

    Science.gov (United States)

    Anderson, Leif F.; Harrington, Sean P.; Omeke, Ojei, II; Schwaab, Douglas G.

    2009-01-01

    This is a case study on revised estimates of induced failure for International Space Station (ISS) on-orbit replacement units (ORUs). We devise a heuristic to leverage operational experience data by aggregating ORU, associated function (vehicle sub -system), and vehicle effective' k-factors using actual failure experience. With this input, we determine a significant failure threshold and minimize the difference between the actual and predicted failure rates. We conclude with a discussion on both qualitative and quantitative improvements the heuristic methods and potential benefits to ISS supportability engineering analysis.

  18. Feasibility study for lowering the minimum gas pressure in solution-mined caverns based on geomechanical analyses of creep-induced damage and healing

    Energy Technology Data Exchange (ETDEWEB)

    Ratigan, J.L.; Nieland, J.D.; Devries, K.L.

    1998-12-31

    Geomechanical analyses were made to determine the minimum gas pressure allowable based on an existing stress-based criterion (Damage Potential) and an advanced constitutive model (MDCF model) capable of quantifying the level of damage and healing in rock salt. The MDCF model is a constitutive model developed for the WIPP to provide a continuum description of the dislocation and damage deformation of salt. The purpose of this study was to determine if the MDCF model is applicable for evaluating the minimum gas pressure of CNG storage caverns. Specifically, it was to be determined if this model would predict that the minimum gas pressure in the caverns could be lowered without compromising the stability of the cavern. Additionally, the healing behavior of the salt was analyzed to determine if complete healing of the damaged rock zone would occur during the period the cavern was at maximum gas pressure. Significant findings of this study are reported.

  19. Tidal Energy Resource Assessment in Chacao Channel, Chile

    Science.gov (United States)

    Guerra, M.; Suarez, L.; Cienfuegos, R.; Thomson, J. M.

    2014-12-01

    The Chacao Channel, located in Los Lagos region in Chile (41º S; 73º W), is a highly energetic tidal channel, with a complex hydrodynamics resulting from the propagation of tidal waves through a narrow channel. The channel flow exhibits bi-directional tidal currents up to 4 to 5 m/s along with a high tidal range up to 6 m in its east end (Aiken, 2008: Cáceres et al., 2003). The channel has previously been identified as one of the most attractive sites in Chile for tidal energy extraction (Garrad Hassan and Partners, 2009); however this statement is based on global model predictions over coarse bathymetric information. In this investigation, the first hydrodynamic characterization of the Chacao channel is carried out in order to assess the hydrokinetic power available and to select the most interesting spots where the first tidal energy extraction devices might be installed in Chile. The Chacao channel hydrodynamic characterization and resource assessment is carried out in two stages: field measurements and numerical hydrodynamic modeling. The first stage involves a 10 m resolution multi-beam bathymetry of the channel, sea-level measurements using 6 tidal gauges distributed over the channel berms, tidal current measurements with 6 ADCPs distributed along the channel, and detailed measurements of turbulence in a specific spot in the channel using the Tidal Turbulence Mooring (TTM) developed by Thomson et al. (2013). In a second stage, numerical hydrodynamic modeling using FVCOM (Chen et al., 2003) was prepared for the entire Chacao channel region, using the field data collected in the first stage for calibration and validation of the model. The obtained results allow us to define suitable sites for marine energy extraction, finding large areas with 30 to 60 m depths where horizontal currents are above 1.5 m/s during 60% of the time of a 28 days tidal cycle, however the high levels of turbulence detected by the TTM indicate the need for more detailed studies on the

  20. Postural-induced changes in intracranial pressure evaluated non-invasively using the MMS-10 tympanic displacement analyser in healthy volunteers.

    Science.gov (United States)

    Wagner, N; Walsted, A

    2000-01-01

    Inner ear pressure reflects intracranial pressure (ICP) primarily because of the direct communication of perilymph and cerebrospinal fluid (CSF) through the cochlear aqueduct (CA). The MMS-10 tympanic displacement analyser (TDA) is a relatively new device for measuring perilymphatic pressure non-invasively, and thereby also indirectly measuring intracranial pressure. The aim of the present study was to evaluate the use of the TDA in a daily clinical setting. Other aims were to investigate changes in perilymphatic pressure from sitting to lying position in healthy volunteers in two age groups (mean age: 33 years and 50 years) and to compare the patency of the CA in these groups using the MMS-10 TDA. Tympanic membrane displacement (TMD) analyses were performed in the test subjects initially twice in sitting position (test-retest) and then in sitting and supine positions. We found that the MMS-10 TDA is easy to use, and that it gives reproducible values in repeated tests, but with large inter-subject differences. The TMD test showed curves, which, in the whole test group, were more negative in supine position, in accordance with an increasing intracranial and inner ear pressure when lying down. The change from sitting to lying position was larger in the younger group than in the older group. In 11% of the younger group (males) and in 30% of the older group (females), the CA was considered to be non-patent, although the difference was not statistically significant. However, the finding is in keeping with the hypothesis of a greater proportion of patent CA in younger than in older individuals.

  1. Incorporating future change into current conservation planning: Evaluating tidal saline wetland migration along the U.S. Gulf of Mexico coast under alternative sea-level rise and urbanization scenarios

    Science.gov (United States)

    Enwright, Nicholas M.; Griffith, Kereen T.; Osland, Michael J.

    2015-11-02

    In this study, the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, quantified the potential for landward migration of tidal saline wetlands along the U.S. Gulf of Mexico coast under alternative future sea-level rise and urbanization scenarios. Our analyses focused exclusively on tidal saline wetlands (that is, mangrove forests, salt marshes, and salt flats), and we combined these diverse tidal saline wetland ecosystems into a single grouping, “tidal saline wetland.” Collectively, our approach and findings can provide useful information for scientists and environmental planners working to develop future-focused adaptation strategies for conserving coastal landscapes and the ecosystem goods and services provided by tidal saline wetlands. The primary product of this work is a public dataset that identifies locations where landward migration of tidal saline wetlands is expected to occur under alternative future sea-level rise and urbanization scenarios. In addition to identifying areas where landward migration of tidal saline wetlands is possible because of the absence of barriers, these data also identify locations where landward migration of these wetlands could be prevented by barriers associated with current urbanization, future urbanization, and levees.

  2. Anti-obesity effect of radix Angelica sinensis and candidate causative genes in transcriptome analyses of adipose tissues in high-fat diet-induced mice.

    Science.gov (United States)

    Zhong, Tao; Zhang, Hao; Duan, Xiaoyue; Hu, Jiangtao; Wang, Linjie; Li, Li; Zhang, Hongping; Niu, Lili

    2017-01-30

    We have previously reported that radix Angelica sinensis (RAS) suppressed body weight and altered the expression of the fat mass and obesity associated (FTO) gene in mice with high fat diet (HFD)-induced obesity. In the present study we performed RNA sequencing-mediated transcriptome analysis to elucidate the molecular mechanisms underlying the anti-obesogenic effects of RAS in mice. The results revealed that 36 differentially-expressed genes (DEGs) were identified in adipose tissues from the RAS supplementation group (DH) and control group (HC). These 36 DEGs were clustered into 297 functional gene ontology (GO) categories, among which several GO annotations and signaling pathways were associated with lipid homeostasis. Six out of the 36 DEGs were identified to be involved in lipid metabolism, with the APOA2 gene a potential anti-obesogenic influence. The expression pattern revealed by RNA-Seq was identical to the results of quantitative real-time PCR (qPCR). Therefore, RAS supplementation in HFD-induced obese mice was associated with an anti-obesogenic global transcriptomic response. This study provides insight into potential applications of RAS in obesity therapy.

  3. Tidal currents in the Yucatan Channel

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo Gonzalez, Fatima [Centro Universitario de la Costa, Universidad de Guadalajara, Guadalajara, Jalisco (Mexico); Ochoa, Jose; Candela, Julio; Badan, Antonio; Sheinbaum; Gonzalez Navarro, Juan Ignacio [Departamento de Oceanografia Fisica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Ensenada, Baja California (Mexico)

    2007-07-15

    Currents data from a ten-month period at 197 measuring points covering all Yucatan Channel were processed by harmonic analysis to estimate tidal parameters for the O{sub 1}, K{sub 1}, M{sub 2} and S{sub 2} components. The highly detailed coverage confirms the known dominance for the O{sub 1} and K{sub 1} diurnal components, but also showed, for the first time, their intensification in the deep eastern margin of the channel where maximum amplitudes in main axis are 17 and 19 cm.s{sup -}1. The data also confirms weak semi-diurnal components, of which the most intense, M{sub 2} and S{sub 2}, have amplitudes only up to 2 cm.s{sup -}1. The tidal ellipses were elongated (i.e. with eccentricities close to one) in the NNW direction. The O{sub 1}, K{sub 1}, M{sub 2} and S{sub 2} contributions in transport variability through the channel have amplitudes of 11.7, 12.5, 1.2 and 1.0 Sv, all well determined above noise. [Spanish] Se presentan, a detalle sin precedente, las caracteristicas de las corrientes de marea O{sub 1}, K{sub 1}, M{sub 2} y S{sub 2} en el canal de Yucatan. Mapas de los parametros que definen las elipses, como son las amplitudes en los ejes principales, la orientacion, la fase y la razon-senal-ruido se obtienen, por el clasico analisis armonico en mediciones de 10 meses en duracion, en 197 puntos que cubren ampliamente un plano vertical del canal. En acuerdo con reportes anteriores, las senales diurnas O{sub 1} y K{sub 1} dominan, demostrandose aqui que sus amplitudes alcanzan, en la parte profunda y Este, 17 y 19 cm.s{sup -}1. El analisis tambien revela senales semidiurnas M{sub 2} y S{sub 2} muy debiles con amplitudes maximas de 2 y 1cm.s{sup -}1. Las elipses son muy alargadas (i.e. con excentricidad cercana a uno) y orientadas al nornoroeste. Los valores de la razon senal a ruido indican que los parametros de las dos constituyentes diurnas se encuentran bien determinados, mientras que las semidiurnas quedan muy contaminadas por el ruido. El rasgo mas

  4. Qualitative tissue differentiation by analysing the intensity ratios of atomic emission lines using laser induced breakdown spectroscopy (LIBS): prospects for a feedback mechanism for surgical laser systems.

    Science.gov (United States)

    Kanawade, Rajesh; Mahari, Fanuel; Klämpfl, Florian; Rohde, Maximilian; Knipfer, Christian; Tangermann-Gerk, Katja; Adler, Werner; Schmidt, Michael; Stelzle, Florian

    2015-01-01

    The research work presented in this paper focuses on qualitative tissue differentiation by monitoring the intensity ratios of atomic emissions using 'Laser Induced Breakdown Spectroscopy' (LIBS) on the plasma plume created during laser tissue ablation. The background of this study is to establish a real time feedback control mechanism for clinical laser surgery systems during the laser ablation process. Ex-vivo domestic pig tissue samples (muscle, fat, nerve and skin) were used in this experiment. Atomic emission intensity ratios were analyzed to find a characteristic spectral line for each tissue. The results showed characteristic elemental emission intensity ratios for the respective tissues. The spectral lines and intensity ratios of these specific elements varied among the different tissue types. The main goal of this study is to qualitatively and precisely identify different tissue types for tissue specific laser surgery.

  5. Linking channel hydrology with riparian wetland accretion in tidal rivers

    Science.gov (United States)

    Ensign, Scott H.; Noe, Gregory B.; Hupp, Cliff R.

    2014-01-01

    hydrologic processes by which tide affects river channel and riparian morphology within the tidal freshwater zone are poorly understood yet are fundamental to predicting the fate of coastal rivers and wetlands as sea level rises. We investigated patterns of sediment accretion in riparian wetlands along the nontidal through oligohaline portion of two coastal plain rivers in Maryland, U.S., and how flow velocity, water level, and suspended sediment concentration (SSC) in the channel may have contributed to those patterns. Sediment accretion was measured over a 1 year period using artificial marker horizons, channel hydrology was measured over a 1 month period using acoustic Doppler current profilers, and SSC was predicted from acoustic backscatter. Riparian sediment accretion was lowest at the nontidal sites (mean and standard deviation = 8 ± 8 mm yr-1), highest at the upstream tidal freshwater forested wetlands (TFFW) (33 ± 28 mm yr-1), low at the midstream TFFW (12 ± 9 mm yr-1), and high at the oligohaline (fresh-to-brackish) marshes (19 ± 8 mm yr-1). Channel maximum flood and ebb velocity was twofold faster at the oligohaline than tidal freshwater zone on both tidal rivers, corresponding with the differences in in-channel SSC: The oligohaline zone's SSC was more than double the tidal freshwater zone's and was greater than historical SSC at the nontidal gages. The tidal wave characteristics differed between rivers, leading to significantly greater in-channel SSC during floodplain inundation in the weakly convergent than the strongly convergent tidal river. High sediment accretion at the upstream TFFW was likely due to high river discharge following a hurricane.

  6. Canada ocean energy atlas phase 1 : potential tidal current energy resources analysis background

    Energy Technology Data Exchange (ETDEWEB)

    Tarbotton, M.; Larson, M. [Triton Consultants Ltd., Vancouver, BC (Canada)

    2006-05-15

    This report was prepared as a background document for a preliminary tidal current resource inventory for Canadian waters. Energy calculations in the study were based on preliminary estimates of known tidal flows. The inventory was based on nautical charts, Canadian sailing directions, tide and tidal current constituent data, and numerical tidal modelling data. A finite element harmonic tidal model tool was used to provide tidal height and current velocities data for a varying number of tidal constituents. The study identified several major tidal current power resources throughout Canada. It was concluded that modelling studies should concentrate on Minas Basin in Nova Scotia; Georgia and Johnstone Straits in British Columbia; and Hudson's Strait and Ungava Bay. Modelling studies should provide estimates of extractable energy as well as provide initial assessments of the environmental impacts of tidal energy extraction in all 3 regions. 3 refs., 8 tabs., 16 figs.

  7. 2-dimensional mapping of ICRF-induced scrape-off layer modifications with a retarding field analyser on ASDEX-Upgrade

    Science.gov (United States)

    Colas, L.; Bobkov, V.; Carralero, D.; Kočan, M.; Müller, H. W.; Manz, P.; Kubič, M.; Gunn, J. P.; Herrmann, A.; Rohde, V.; ASDEX-Upgrade Team

    2014-02-01

    Using a reciprocating Retarding Field Analyser (RFA), Scrape-Off Layer (SOL) modifications were investigated on ASDEX-Upgrade during heating with waves in the Ion Cyclotron Range of Frequencies (ICRF), suspected for enhanced impurity production in this all-metal machine. Two quantities involved in the sputtering were measured: the current Islit on a saturated slit plate, proportional to the parallel ion flux and the mean parallel energy t of collected ions, averaged over many RF cycles. Combining multiple RFA reciprocations over a scan of q95 provided 2D poloidal/radial resolution. In the outer SOL a localized RF-perturbed zone was evidenced on the RFA side magnetically connected to an active ICRF antenna. A flat 2D Islit pattern surrounded by steep gradients was observed, correlatively with t exceeding 150eV. The centre of the zone is connected radially slightly behind the leading edge of antenna side limiters, with a radial extension up to ±2cm. The zone is broadest and t is largest near the bottom of the active antenna. This is interpreted as a zone of local plasma biasing via sheath rectification, creating density convection around it. The Islit pattern is qualitatively consistent with simple considerations about E×B particle convection.

  8. [Investigation of Predisposition Biomarkers to Identify Risk Factors for Drug-induced Liver Injury in Humans: Analyses of Endogenous Metabolites in an Animal Model Mimicking Human Responders to APAP-induced Hepatotoxicity].

    Science.gov (United States)

    Kobayashi, Akio; Kondo, Kazuma; Sugai, Shoichiro

    2015-01-01

    Drug-induced liver injury is a main reason of regulatory action pertaining to drugs, including restrictions to clinical indications and withdrawal from the marketplace. Acetaminophen (APAP) is a commonly used and effective analgesic/antipyretic agent and relatively safe drug even in long-term treatment. However, it is known that APAP at therapeutic doses may cause hepatotoxicity in some individuals. Hence great efforts have been made to identify risk factors for APAP-induced chronic hepatotoxicity. We investigated the contribution of undernourishment to susceptibility to APAP-induced chronic hepatotoxicity using an animal model. We employed daytime restricted fed (RF) rats as a modified-nutritional state model for human APAP-induced hepatotoxicity. RF and ad libitum fed (ALF) rats were given APAP at 0, 300, and 500 mg/kg for 3 months. Plasma and urinary glutathione-related metabolomes and liver function parameters were measured during the dosing period. Endogenous metabolites forming at different levels between the RF and ALF rats could be potential predisposition biomarkers for APAP-induced hepatotoxicity. In addition, RF rats were considered a useful model to estimate the contribution of nutritional state of patients to APAP-induced chronic hepatotoxicity. In this article we report our current research focusing on nutritional state as risk factor for APAP-induced chronic hepatotoxicity and our findings of hepatotoxicity biomarkers.

  9. Tidal Origin of Spiral Arms in Galaxies Orbiting a Cluster

    Science.gov (United States)

    Semczuk, Marcin; Łokas, Ewa L.; del Pino, Andrés

    2017-01-01

    One of the scenarios for the formation of grand-design spiral arms in disky galaxies involves their interactions with a satellite or another galaxy. Here we consider another possibility, where the perturbation is instead due to the potential of a galaxy cluster. Using N-body simulations we investigate the formation and evolution of spiral arms in a Milky-Way-like galaxy orbiting a Virgo-like cluster. The galaxy is placed on a few orbits of different size but similar eccentricity and its evolution are followed for 10 Gyr. The tidally induced, two-armed, approximately logarithmic spiral structure forms on each of them during the pericenter passages. The spiral arms dissipate and wind up with time, to be triggered again at the next pericenter passage. We confirm this transient and recurrent nature of the arms by analyzing the time evolution of the pitch angle and the arm strength. We find that the strongest arms are formed on the tightest orbit; however, they wind up rather quickly and are disturbed by another pericenter passage. The arms on the most extended orbit, which we analyze in more detail, wind up slowly and survive for the longest time. Measurements of the pattern speed of the arms indicate that they are kinematic density waves. We attempt a comparison with observations by selecting grand-design spiral galaxies in the Virgo cluster. Among those, we find nine examples bearing no sign of recent interactions or the presence of companions. For three of them we present close structural analogues among our simulated spiral galaxies.

  10. Relationships between diatoms and tidal environments in Oregon and Washington, USA

    Science.gov (United States)

    Sawai, Yuki; Horton, Benjamin P.; Kemp, Andrew C.; Hawkes, Andrea D.; Nagumo, Tamostsu; Nelson, Alan R.

    2016-01-01

    A new regional dataset comprising 425 intertidal diatom taxa from 175 samples from 11 ecologically diverse Oregon and Washington estuaries illustrates the importance of compiling a large modern dataset from a range of sites. Cluster analyses and detrended correspondence analysis of the diatom assemblages identify distinct vertical zones within supratidal, intertidal and subtidal environments at six of the 11 study sites, but the abundance of some of the most common species varies widely among and within sites. Canonical correspondence analysis of the regional dataset shows relationships between diatom species and tidal exposure, salinity and substratum (grain size and organic content). Correspondence analyses of local datasets show higher values of explained variation than the analysis of the combined regional dataset. Our results emphasize that studies of the autecology of diatom species require many samples from a range of modern environments to adequately characterize species–environment relationships.

  11. Suppression mechanism of radiation-induced darkening by Ce doping in Al/Yb/Ce-doped silica glasses: Evidence from optical spectroscopy, EPR and XPS analyses

    Science.gov (United States)

    Shao, Chongyun; Xu, Wenbin; Ollier, Nadege; Guzik, Malgorzata; Boulon, Georges; Yu, Lu; Zhang, Lei; Yu, Chunlei; Wang, Shikai; Hu, Lili

    2016-10-01

    Yb3+/Al3+ co-doped silica glasses with different Ce2O3 contents were prepared using the sol-gel method combined with high-temperature sintering. Changes in refractive index, absorption, emission and fluorescence lifetime of these glasses caused by X-ray irradiation were recorded and analyzed systematically. It is found that co-doping with certain amount of Ce could greatly improve the radiation resistance without evident negative effects on the basic optical properties of the Yb3+ ions in the near-infrared region. The nature of the radiation-induced color centres and the mechanism by which Ce prevented the formation of these centres were studied using optical absorption, electron paramagnetic resonance (EPR), and X-ray photoelectron spectroscopy (XPS) methods. Direct evidence confirmed that trapped electron centres (Yb2+/Si-E'/Al-E') and trapped hole centres (Al-OHCs) were effectively inhibited by Ce doping, which was correlated to the coexistence of the redox couple Ce3+/Ce4+ in the glasses. These results are helpful to understand the micro-structural origin and the suppression mechanism by Ce co-doping of the photodarkening effect in Yb3+-doped silica fibers.

  12. Honing in on phenotypes: comprehensive two-dimensional gas chromatography of herbivory-induced volatile emissions and novel opportunities for system-level analyses.

    Science.gov (United States)

    Gaquerel, Emmanuel; Baldwin, Ian T

    2013-01-01

    Plant volatile organic compound (VOC) production requires a complex network of biochemical pathways, which, although well mapped from a biochemical point of view, remains only partly understood with regard to its physiological and genetic regulation. Additionally, although analytical procedures for plant VOC measurement have become increasingly faster and more sensitive in recent years, pinpointing relevant shifts in VOC production from the thousands of molecular fragments that are generated by modern mass spectrometer instruments remains challenging. Here we discuss novel opportunities for system-wide analysis provided by the implementation of non-targeted data processing and multivariate statistics in VOC analysis. We illustrate the value of implementing non-targeted data processing with examples of recent findings from our group on the interactive control exerted by salivary components of a lepidopteran herbivore, Manduca sexta, on herbivory-induced VOC emissions in the wild tobacco Nicotiana attenuata. Finally, we briefly discuss the use of multi-platform data integration for probing the nature of metabolic and regulatory systems underlying VOC emissions.

  13. Chromium- and copper-induced inhibition of photosynthesis in Euglena gracilis analysed on the single-cell level by fluorescence kinetic microscopy.

    Science.gov (United States)

    Rocchetta, Iara; Küpper, Hendrik

    2009-01-01

    Here, we investigated effects of copper (Cu) and chromium (Cr) toxicity on two contrasting strains of Euglena gracilis, with and without chloroplasts, grown in culture media promoting either phototrophic or heterotrophic growth. This led to insights into Cr/Cu toxicity mechanisms and into the regulation of phototrophic vs heterotrophic metabolism. Our data strongly suggest that in Cu(2+) and Cr(6+) stressed Euglena photosynthesis is the primary target of damage. In the applied light conditions, this was mainly damage to the photosystem II reaction centre, as shown by single-cell measurements of photochemical fluorescence quenching. Respiration and photosynthetic dark reactions were less sensitive. The malfunctioning photosynthesis enhanced production of reactive oxygen species (mainly superoxide), leading to elevated amounts of carotenoid degradation products. At higher metal concentrations in chloroplast-containing cells, but not white cells, this oxidative stress resulted in increased respiratory oxygen uptake, likely by damage to mitochondria. During growth in nutrient solution promoting heterotrophic metabolism, the cells were able to repair the metal-induced damage to photosynthesis, moderating the inhibition of photochemistry. Growth in medium forcing the cells into photosynthesis increased the investment in photosynthetic pigments. Comparison of the two Euglena strains surprisingly showed that the previously metal-resistant strain lost this resistance during culture.

  14. A unified treatment of tidal disruption by Schwarzschild black holes

    CERN Document Server

    Servin, Juan

    2016-01-01

    Stars on orbits with pericenters sufficiently close to the supermassive black hole at the center of their host galaxy can be ripped apart by tidal stresses. Some of the resulting stellar debris becomes more tightly bound to the hole and can potentially produce an observable flare called a tidal-disruption event (TDE). We provide a self-consistent, unified treatment of TDEs by non-spinning (Schwarzschild) black holes, investigating several effects of general relativity including changes to the boundary in phase space that defines the loss-cone orbits on which stars are tidally disrupted or captured. TDE rates decrease rapidly at large black-hole masses due to direct stellar capture, but this effect is slightly countered by the widening of the loss cone due to the stronger tidal fields in general relativity. We provide a new mapping procedure that translates between Newtonian gravity and general relativity, allowing us to better compare predictions in both gravitational theories. Partial tidal disruptions in re...

  15. Jeans instability criterion modified by external tidal field

    CERN Document Server

    Jog, Chanda J

    2013-01-01

    The well-known Jeans criterion describes the onset of instabilities in an infinite, homogeneous, self-gravitating medium supported by pressure. Most realistic astrophysical systems, however, are not isolated - instead they are under the influence of an external field such as the tidal field due to a neighbour. Here we do a linear perturbation analysis for a system in an external field, and obtain a generalized dispersion relation that depends on the wavenumber, the sound speed, and also the magnitude of the tidal field. A typical, disruptive tidal field is shown to make the system more stable against perturbations, and results in a higher effective Jeans wavelength. The minimum mass that can become unstable is then higher (super-Jeans) than the usual Jeans mass. Conversely, in a compressive tidal field, perturbations can grow even when the mass is lower (sub-Jeans). This approach involving the inclusion of tidal field opens up a new way of looking at instabilities in gravitating systems. The treatment is gene...

  16. Long-Term Morphological Modeling of Barrier Island Tidal Inlets

    Directory of Open Access Journals (Sweden)

    Richard Styles

    2016-09-01

    Full Text Available The primary focus of this study is to apply a two-dimensional (2-D coupled flow-wave-sediment modeling system to simulate the development and growth of idealized barrier island tidal inlets. The idealized systems are drawn from nine U.S. coastal inlets representing Pacific Coast, Gulf Coast and Atlantic Coast geographical and climatological environments. A morphological factor is used to effectively model 100 years of inlet evolution and the resulting morphological state is gauged in terms of the driving hydrodynamic processes. Overall, the model performs within the range of established theoretically predicted inlet cross-sectional area. The model compares favorably to theoretical models of maximum inlet currents, which serve as a measure of inlet stability. Major morphological differences are linked to inlet geometry and tidal forcing. Narrower inlets develop channels that are more aligned with the inlet axis while wider inlets develop channels that appear as immature braided channel networks similar to tidal flats in regions with abundant sediment supply. Ebb shoals with strong tidal forcing extend further from shore and spread laterally, promoting multi-lobe development bisected by ebb shoal channels. Ebb shoals with moderate tidal forcing form crescent bars bracketing a single shore-normal channel. Longshore transport contributes to ebb shoal asymmetry and provides bed material to help maintain the sediment balance in the bay.

  17. 3-D Simulation of Vertical-Axial Tidal Current Turbine

    Directory of Open Access Journals (Sweden)

    Zhiyang Zhang

    2016-12-01

    Full Text Available Vertical-axial tidal current turbine is the key for the energy converter, which has the advantages of simple structure, adaptability to flow and uncomplex convection device. It has become the hot point for research and application recently. At present, the study on the hydrodynamic performance of vertical-axial tidal current turbine is almost on 2-D numerical simulation, without the consideration of 3-D effect. CFD (Computational Fluid Dynamics method and blade optimal control technique are used to improve accuracy in the prediction of tidal current turbine hydrodynamic performance. Numerical simulation of vertical-axial tidal current turbine is validated. Fixed and variable deflection angle turbine are comparatively studied to analysis the influence of 3-D effect and the character of fluid field and pressure field. The method, put the plate on the end of blade, of reduce the energy loss caused by 3-D effect is proposed. The 3-D CFD numerical model of vertical-axial tidal current turbine hydrodynamic performance in this study may provide theoretical, methodical and technical reference for the optimal design of turbine.

  18. Tidal generation of large sub-mesoscale eddy dipoles

    Directory of Open Access Journals (Sweden)

    W. Callendar

    2011-08-01

    Full Text Available Numerical simulations of tidal flow past Cape St. James on the south tip of Haida Gwaii (Queen Charlotte Islands are presented that indicate mesoscale dipoles are formed from coalescing tidal eddies. Observations in this region demonstrate robust eddy generation at the Cape, with the primary process being flow separation of buoyant or wind driven outflows forming large anti-cyclonic, negative potential vorticity, Haida Eddies. However, there are other times where dipoles are observed in satellites, indicating a source of positive potential vorticity must also be present. The simulations here build on previous work that implicates oscillating tidal flow past the cape in creating the positive vorticity. Small headland eddies of alternating vorticity are created each tide. During certain tidal cycles, the headland eddies coalesce and self organize in such a way as to create large >20-km diameter eddies that then self-advect into deep water. The self advection speed is faster than the beta drift of anti-cyclones, and the propagation direction appears to be more southerly than typical Haida Eddies, though the model contains no mean wind-driven flows. These eddies are smaller than Haida Eddies, but given their tidal origin, may represent a more consistent source of coastal water that is injected into the interior of the subpolar gyre.

  19. Tidal generation of large sub-mesoscale eddy dipoles

    Science.gov (United States)

    Callendar, W.; Klymak, J. M.; Foreman, M. G. G.

    2011-08-01

    Numerical simulations of tidal flow past Cape St. James on the south tip of Haida Gwaii (Queen Charlotte Islands) are presented that indicate mesoscale dipoles are formed from coalescing tidal eddies. Observations in this region demonstrate robust eddy generation at the Cape, with the primary process being flow separation of buoyant or wind driven outflows forming large anti-cyclonic, negative potential vorticity, Haida Eddies. However, there are other times where dipoles are observed in satellites, indicating a source of positive potential vorticity must also be present. The simulations here build on previous work that implicates oscillating tidal flow past the cape in creating the positive vorticity. Small headland eddies of alternating vorticity are created each tide. During certain tidal cycles, the headland eddies coalesce and self organize in such a way as to create large >20-km diameter eddies that then self-advect into deep water. The self advection speed is faster than the beta drift of anti-cyclones, and the propagation direction appears to be more southerly than typical Haida Eddies, though the model contains no mean wind-driven flows. These eddies are smaller than Haida Eddies, but given their tidal origin, may represent a more consistent source of coastal water that is injected into the interior of the subpolar gyre.

  20. Tidal generation of large sub-mesoscale eddy dipoles

    Directory of Open Access Journals (Sweden)

    W. Callendar

    2011-04-01

    Full Text Available Numerical simulations of tidal flow past Cape St. James on the south tip of Haida Gwai (Queen Charlotte Islands are presented that indicate mesoscale dipoles are formed from coalescing tidal eddies. Observations in this region demonstrate robust eddy generation at the Cape, with the primary process being flow separation of buoyant or wind driven outflows forming large anti-cyclonic, negative potential vorticity, Haida Eddies. However, there are other times where dipoles are observed in satellites, indicating a source of positive potential vorticity must also be present. The simulations here build on previous work that implicates oscillating tidal flow past the cape in creating the positive vorticity. Small headland eddies of alternating vorticity are created each tide. During certain tidal cycles, the headland eddies coalesce and self organize in such a way as to create large >20-km diameter eddies that then self-advect into deep water. The self advection speed is faster than the beta drift of anti-cyclones, and the propagation direction appears to be more southerly than typical Haida Eddies, though the model contains no mean wind-driven flows. These eddies are smaller than Haida Eddies, but given their tidal origin, may represent a more consistent source of coastal water that is injected into to the interior of the subpolar gyre.

  1. Variability in tidal disruption events: gravitationally unstable streams

    CERN Document Server

    Coughlin, Eric R

    2015-01-01

    We present simulations of the tidal disruption of a solar mass star by a $10^6M_{\\odot}$ black hole. These, for the first time, cover the full time evolution of the tidal disruption event, starting well before the initial encounter and continuing until more than 90% of the bound material has returned to the vicinity of the hole. Our results are compared to the analytical prediction for the rate at which tidally-stripped gas falls back. We find that, for our chosen parameters, the overall scaling of the fallback rate, $\\dot{M}_{\\rm{fb}}$, closely follows the canonical $t^{-5/3}$ power-law. However, our simulations also show that the self-gravity of the tidal stream, which dominates the tidal gravity of the hole at large distances, causes some of the debris to recollapse into bound fragments before returning to the hole. This causes $\\dot{M}_{\\rm{fb}}$ to vary significantly around the $t^{-5/3}$ average. We discuss the implications of our findings in the context of the event Swift J1644+57.

  2. Bar morphodynamics in the tidally-influenced fluvial zone

    Science.gov (United States)

    Parsons, Daniel; Ashworth, Philip; Best, James; Nicholas, Andrew; Prokocki, Eric; Sambrook-Smith, Greg; Keevil, Claire; Sandbach, Steve

    2015-04-01

    The hydrodynamics and deposits of the Tidally-Influenced Fluvial Zone (TIFZ) are complex because it experiences competing fluvial and tidal flows and spatially and temporally variable rates of sediment transport and deposition. This paper presents a new integrated field dataset from the Columbia River Estuary, USA, that quantifies the morphodynamic response the bed morphology and bar stratigraphy to fluvial-tidal flows. A 3-year, field and modelling program that started in 2011, has been monitoring the dynamics and deposits of a 40 km-reach of the Columbia River Estuary. Data obtained so far throughout the TIFZ include: bathymetry using MBES, flow using ADCP, subsurface sedimentology using GPR and shallow coring to 5 m. Initial results from the programme suggest there is a complex spatial and temporal lag in the response of the bed morphology and deposits to the fluvial-tidal flows. Zones of strong ebb and flood flow do not necessarily produce channel beds dominated by bi-directional bedforms. Many mid-channel bars are stable over decadal time periods. This paper will illustrate the variety in bar morphologies and channel change throughout the fluvial-tidal zone and contrast these bar dynamics with examples from purely fluvial environments.

  3. Bar morphodynamics in the fluvial-tidal zone

    Science.gov (United States)

    Ashworth, P. J.; Best, J. L.; Nicholas, A.; Parsons, D. R.; Prokocki, E.; Sambrook Smith, G.; Simpson, C.

    2012-12-01

    The hydrodynamics and deposits of the Tidally-Influenced Fluvial Zone (TIFZ) are complex because it experiences competing fluvial and tidal flows, sometimes moderated by waves, and spatially and temporally variable rates of sediment transport and deposition. This paper presents a new integrated field dataset from the Columbia River Estuary, USA, that quantifies the response of the flow structure, bed morphology and bar stratigraphy to fluvial-tidal flows. A new 3-year, field and modelling program that started in 2011, has been monitoring the dynamics and deposits of a 40 km-reach of the Columbia River Estuary. Data obtained so far throughout the TIFZ include: bathymetry using MBES, flow using ADCP, subsurface sedimentology using GPR and shallow coring to 5 m. First results suggest there is a complex spatial and temporal lag in the response of the bed morphology and deposits to the fluvial-tidal flows. Zones of strong ebb and flood flow do not necessarily produce channel beds dominated by bi-directional bedforms. Many mid-channel bars are stable over decadal time periods. This paper will illustrate the variety in bar morphologies and channel change throughout the fluvial-tidal zone and contrast these bar dynamics with examples from purely fluvial environments.

  4. Ultraviolet and optical observations of tidal disruption events

    Directory of Open Access Journals (Sweden)

    Gezari S.

    2012-12-01

    Full Text Available Tidal disruption events are expected to produce a luminous flare of radiation from fallback accretion of tidally disrupted stellar debris onto the central supermassive black hole. The first convincing candidates for tidal disruption events were discovered in the soft X-rays: large-amplitude, luminous, extremely-soft X-ray flares from inactive galaxies in the ROSAT All-Sky survey. However, the sparsely sampled light curves and lack of multiwavelength observations for these candidates make it difficult to directly constrain the parameters of their events (e.g., Eddington ratio, mass of the black hole, type of star disrupted. Here I present a review of the recent progress made in studying tidal disruption events in detail from taking advantage of wide-field, multi-epoch observations of UV and optical surveys (GALEX, SDSS, PTF, Pan-STARRS1 to measure well-sampled light curves, trigger prompt multiwavelength follow-up observations, and measure rates. I conclude with the promising potential of the next generation of optical synoptic surveys, such as LSST, to probe black hole demographics with samples of thousands of tidal disruption events.

  5. Multiple tidal disruption flares in the active galaxy IC 3599

    CERN Document Server

    Campana, S; Colpi, M; Lodato, G; D'Avanzo, P; Evans, P A; Moretti, A

    2015-01-01

    Tidal disruption events occur when a star passes too close to a massive black hole and it is totally ripped apart by tidal forces. Alternatively, if the star does not get close enough to the black hole to be totally disrupted, a less dramatic event might happen with the star surviving the encounter and loosing only a small fraction of its mass. In this situation if the stellar orbit is bound and highly eccentric, just like some stars in the centre of our own Galaxy, repeated flares should occur. When the star approaches the black hole tidal radius at periastron, matter might be stripped resulting in lower intensity outbursts recurring once every orbital period. We report on Swift observations of a recent bright flare from the galaxy IC 3599 hosting a middle-weight black hole, where a possible tidal disruption event was observed in the early 1990s. By light curve modelling and spectral fitting we can consistently account for the events as the non-disruptive tidal stripping of a star into a highly eccentric orb...

  6. Latent resonance in tidal rivers, with applications to River Elbe

    Science.gov (United States)

    Backhaus, Jan O.

    2015-11-01

    We describe a systematic investigation of resonance in tidal rivers, and of river oscillations influenced by resonance. That is, we explore the grey-zone between absent and fully developed resonance. Data from this study are the results of a one-dimensional numerical channel model applied to a four-dimensional parameter space comprising geometry, i.e. length and depths of rivers, and varying dissipation and forcing. Similarity of real rivers and channels from parameter space is obtained with the help of a 'run-time depth'. We present a model-channel, which reproduces tidal oscillations of River Elbe in Hamburg, Germany with accuracy of a few centimetres. The parameter space contains resonant regions and regions with 'latent resonance'. The latter defines tidal oscillations that are elevated yet not in full but juvenile resonance. Dissipation reduces amplitudes of resonance while creating latent resonance. That is, energy of resonance radiates into areas in parameter space where periods of Eigen-oscillations are well separated from the period of the forcing tide. Increased forcing enhances the re-distribution of resonance in parameter space. The River Elbe is diagnosed as being in a state of anthropogenic latent resonance as a consequence of ongoing deepening by dredging. Deepening the river, in conjunction with the expected sea level rise, will inevitably cause increasing tidal ranges. As a rule of thumb, we found that 1 m deepening would cause 0.5 m increase in tidal range.

  7. Effects of respiratory rate and tidal volume on gas exchange in total liquid ventilation.

    Science.gov (United States)

    Bull, Joseph L; Tredici, Stefano; Fujioka, Hideki; Komori, Eisaku; Grotberg, James B; Hirschl, Ronald B

    2009-01-01

    Using a rabbit model of total liquid ventilation (TLV), and in a corresponding theoretical model, we compared nine tidal volume-respiratory rate combinations to identify a ventilator strategy to maximize gas exchange, while avoiding choked flow, during TLV. Nine different ventilation strategies were tested in each animal (n = 12): low [LR = 2.5 breath/min (bpm)], medium (MR = 5 bpm), or high (HR = 7.5 bpm) respiratory rates were combined with a low (LV = 10 ml/kg), medium (MV = 15 ml/kg), or high (HV = 20 ml/kg) tidal volumes. Blood gases and partial pressures, perfluorocarbon gas content, and airway pressures were measured for each combination. Choked flow occurred in all high respiratory rate-high volume animals, 71% of high respiratory rate-medium volume (HRMV) animals, and 50% of medium respiratory rate-high volume (MRHV) animals but in no other combinations. Medium respiratory rate-medium volume (MRMV) resulted in the highest gas exchange of the combinations that did not induce choke. The HRMV and MRHV animals that did not choke had similar or higher gas exchange than MRMV. The theory predicted this behavior, along with spatial and temporal variations in alveolar gas partial pressures. Of the combinations that did not induce choked flow, MRMV provided the highest gas exchange. Alveolar gas transport is diffusion dominated and rapid during gas ventilation but is convection dominated and slow during TLV. Consequently, the usual alveolar gas equation is not applicable for TLV.

  8. Displacement and dissipation under the rotating tidal potential, in contrast to Love's geostationary potential

    Science.gov (United States)

    Bostrom, R. C.

    The Earth rotates relative to the solunar gravity field. In consequence the M2, S2 tides are represented by permanent bulges, travelling westward around the Earth as distortion waves. The associated tidal stress ellipsoid progresses perpetually by rotation, without reversal. It is shown that under imperfect elasticity, in lieu of the body forces induced by Love's geostationary time-variant potential a rotating potential induces internal body couples, equally pervasive. Displacement is cumulative, and in the vortical mode formulated by Helmholtz (1858). Whereas in the geostationary formulation of Love cumulative distortion is nil, in actuality this motion is primary, and dimensionally capable of coupling with extant mantle convection. Unlike the marine tides, the bodily wave-tides proceed unhindered around the Earth unhindered by continental margins. Corrected for oceanic effects the complex Love numbers measure dissipation, as commonly supposed. However dissipation is the result of unmapped cumulative vortical displacement (a circulation component), rather than oscillatory forces having the form of a geographically stationary spheroidal eigenvibration. The characteristic period of the loss factor 1/Q is infinity rather than the period pertinent to seismicity or wobble, to which it is dimensionally unrelated. Although primary vorticity-induction is required by the existence of the rotating tidal potential, its tectonic consequences are a matter of speculation, treated elsewhere [1]. --- [1] Bostrom, R.C., 1998. Tectonic Consequences of the Earth's Rotation. Oxfo rd University Press.

  9. Analyses of Patois group bunyaviruses: evidence for naturally occurring recombinant bunyaviruses and existence of immune precipitable and nonprecipitable nonvirion proteins induced in bunyavirus-infected cells.

    Science.gov (United States)

    Ushijima, H; Clerx-Van Haaster, C M; Bishop, D H

    1981-04-30

    Shark River (SR) and Pahayokee (PAH) bunyaviruses (Patois serogroup, Bunyavirus genus, family Bunyaviridae) have almost identical L and S RNA oligonucleotide fingerprints, but M RNA fingerprints that are different, suggesting that the two viruses may represent naturally occurring reassortant viruses. These observations are in agreement with serological studies (B. N. Fields, B. E. Henderson, P. H. Coleman, and T. H. Work, 1969, Amer. J. Epidemiol., 89, 222-226) which have distinguished these two viruses by neutralization of infectivity tests (presumably reflecting differences in M RNA gene products, J. R. Gentsch, E. J. Rozhon, R. A. Klimas, L. H. El Said, R. E. Shope, and D. H. L. Bishop, 1980, Virology102, 190-204), but not by complement fixation tests (which probably relate to the viral N polypeptide coded by the S RNA, J. Gentsch, L. R. Wynne, J. P. Clewley, R. E. Shope, and D. H. L. Bishop, 1977b, J. Virol. 24,893-902). The 3' terminal 11 nucleotides of PAH S RNA (3' (HO)OUCAUCAAAUGA ... 5') are identical in sequence to those of the S RNA species of snowshoe hare (SSH) and La Crosse (LAC) viruses, except for a position 7A residue which is a C residue in the SSH and LAC sequences. The major virion polypeptides of SR and PAH viruses include a nucleocapsid polypeptide (N, 22 x 10(3)) and two glycoproteins (PAH: G1 118 x 10(3), G2, 35 x 10(3); SR: G1 113 x 10(3), G2, 35 x 10(3)). In SR-infected cells several immune precipitable polypeptides have been detected. These include 11-, 54-, 64-, 93-, and 104 x 10(3)-dalton polypeptides. In addition, both SR and PAH viruses induce a 74 x 10(3)-dalton polypeptide (p74) that has not been detected in actinomycin D-treated infected cells, and is not immune precipitated from infected cell extracts.

  10. SEM and Raman spectroscopy analyses of laser-induced periodic surface structures grown by ethanol-assisted femtosecond laser ablation of chromium

    Science.gov (United States)

    Bashir, Shazia; Shahid Rafique, M.; Nathala, Chandra S. R.; Ajami, Ali; Husinsky, Wolfgang

    2015-05-01

    The effect of fluence and pulse duration on the growth of nanostructures on chromium (Cr) surfaces has been investigated upon irradiation of femtosecond (fs) laser pulses in a liquid confined environment of ethanol. In order to explore the effect of fluence, targets were exposed to 1000 pulses at various peak fluences ranging from 4.7 to 11.8 J cm-2 for pulse duration of ∼25 fs. In order to explore the effect of pulse duration, targets were exposed to fs laser pulses of various pulse durations ranging from 25 to 100 fs, for a constant fluence of 11.8 J cm-2. Surface morphology and structural transformations have been analyzed by scanning electron microscopy and Raman spectroscopy, respectively. After laser irradiation, disordered sputtered surface with intense melting and cracking is obtained at the central ablated areas, which are augmented with increasing laser fluence due to enhanced thermal effects. At the peripheral ablated areas, where local fluence is approximately in the range of 1.4-4 mJ cm-2, very well-defined laser-induced periodic surface structures (LIPSS) with periodicity ranging from 270 to 370 nm along with dot-like structures are formed. As far as the pulse duration is concerned, a significant effect on the surface modification of Cr has been revealed. In the central ablated areas, for the shortest pulse duration (25 fs), only melting has been observed. However, LIPSS with dot-like structures and droplets have been grown for longer pulse durations. The periodicity of LIPSS increases and density of dot-like structures decreases with increasing pulse duration. The chemical and structural modifications of irradiated Cr have been revealed by Raman spectroscopy. It confirms the formation of new bands of chromium oxides and enol complexes or Cr-carbonyl compounds. The peak intensities of identified bands are dependent upon laser fluence and pulse duration.

  11. CLIMATE INSTABILITY ON TIDALLY LOCKED EXOPLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Kite, Edwin S.; Manga, Michael [Department of Earth and Planetary Science, University of California at Berkeley, CA 94720 (United States); Gaidos, Eric, E-mail: edwin.kite@gmail.com [Department of Geology and Geophysics, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

    2011-12-10

    Feedbacks that can destabilize the climates of synchronously rotating rocky planets may arise on planets with strong day-night surface temperature contrasts. Earth-like habitable planets maintain stable surface liquid water over geologic time. This requires equilibrium between the temperature-dependent rate of greenhouse-gas consumption by weathering, and greenhouse-gas resupply by other processes. Detected small-radius exoplanets, and anticipated M-dwarf habitable-zone rocky planets, are expected to be in synchronous rotation (tidally locked). In this paper, we investigate two hypothetical feedbacks that can destabilize climate on planets in synchronous rotation. (1) If small changes in pressure alter the temperature distribution across a planet's surface such that the weathering rate goes up when the pressure goes down, a runaway positive feedback occurs involving increasing weathering rate near the substellar point, decreasing pressure, and increasing substellar surface temperature. We call this feedback enhanced substellar weathering instability (ESWI). (2) When decreases in pressure increase the fraction of surface area above the melting point (through reduced advective cooling of the substellar point), and the corresponding increase in volume of liquid causes net dissolution of the atmosphere, a further decrease in pressure will occur. This substellar dissolution feedback can also cause a runaway climate shift. We use an idealized energy balance model to map out the conditions under which these instabilities may occur. In this simplified model, the weathering runaway can shrink the habitable zone and cause geologically rapid 10{sup 3}-fold atmospheric pressure shifts within the habitable zone. Mars may have undergone a weathering runaway in the past. Substellar dissolution is usually a negative feedback or weak positive feedback on changes in atmospheric pressure. It can only cause runaway changes for small, deep oceans and highly soluble atmospheric

  12. Fish communities of a disturbed mangrove wetland and an adjacent tidal river in Palmar, Ecuador

    Science.gov (United States)

    Shervette, V. R.; Aguirre, W. E.; Blacio, E.; Cevallos, Rodrigo; Gonzalez, Marcelo; Pozo, Francisco; Gelwick, F.

    2007-03-01

    Coastal Ecuador has lost 20-30% of mangrove wetlands over the past 30 years. Such habitat loss can impair the ecological functions of wetlands. A paucity of information exists concerning mangrove fish communities of Ecuador. In this study we identify the fish community of the remaining mangrove wetland in Palmar, Ecuador. Fish were sampled in the dry season of 2003 and the wet season of 2004 by seining in mangrove creeks and Main channel of Rio Palmar. For comparison, an adjacent tidal river without mangroves, Rio Javita, was also sampled. We collected a total of 12,231 individuals comprising 36 species in 16 families from Rios Palmar and Javita. Gobiidae (7 species) was the most diverse family for mangrove sites followed by Gerreidae (5 species) and Engraulidae (4 species). A total of 34 species were collected in the mangrove wetland, 21 of which were exclusive to the mangroves including three species of juvenile snook (Centropomidae), indicating that the mangrove habitat of Palmar may provide nursery habitat for these economically valued species. In Rio Javita, Carangidae (3 species) was the most diverse family followed by Engraulidae and Gerreidae (2 species each). A total of 14 species were collected in the tidal river, only two of which were exclusive to the river. Multivariate analyses of fish community data indicated significant differences in community composition between the mangrove creeks and the tidal river and between seasons in both. Juvenile white mullet, Mugil curema, were collected in high relative abundance in both Rios Palmar and Javita, as was the tropical silverside Atherinella serrivomer an ecologically important species. Although Rios Palmar and Javita are characterized by relatively low fish species richness compared to other tropical estuarine systems, they appear to provide an important habitat for several economically and ecologically valued species.

  13. Fidelity of life and death molluscan assemblages from carbonate tidal flats in the Persian (Arabian) Gulf

    Science.gov (United States)

    García-Ramos, Diego A.; Albano, Paolo G.; Harzhauser, Mathias; Piller, Werner E.; Zuschin, Martin

    2016-04-01

    Live-dead (LD) studies aim to help understand how faithfully fossil assemblages can be used to quantitatively infer the structure of the original living communities that generated them. To this purpose, LD comparisons have been conducted in different terrestrial and aquatic environments to assess how environment-specific differences in quality and intensity of taphonomic factors affect LD fidelity. In sub-tropical and tropical settings, most LD studies have focused on hard substrates or seagrass bottoms. Here we present results on molluscan assemblages from soft carbonate sediments in tidal flats of the Persian (Arabian) Gulf (Indo-West Pacific biogeographic province). We analyzed a total of 7193 mollusks collected from six sites comprising time-averaged death assemblages (DAs) and snapshot living assemblages (LAs). All analyses were performed at site and at habitat scales after correcting for sample-size differences. We found a good match in proportional abundance and a notable mismatch in species composition. In fact, species richness in DAs is 6 times larger than in LAs at site scale, and 4 times at habitat scale. Additionally, we found a good fidelity of evenness, and rank abundance of feeding guilds. Other studies have shown that molluscan DAs from subtidal carbonate environments can display lower time-averaging than those from siliciclastic environments due to high rates of shell loss to bioerosion and dissolution. For our case study of tidal flat carbonate settings, we interpret that despite temporal autocorrelation (good fidelity of proportional abundance), substantial differences in species richness and composition can be explained by early cementation, lateral mixing, intense bioturbation and moderate sedimentation rates. Our results suggest that tidal flat carbonate environments can potentially lead to a wider window of time-averaging in comparison with subtidal carbonate settings.

  14. Tidal Disruption of Phobos as the Cause of Surface Fractures

    Science.gov (United States)

    Hurford, T. A.; Asphaug, E.; Spitale, J. N.; Hemingway, D.; Rhoden, A. R.; Henning, W. G.; Bills, B. G.; Kattenhorn, S. A.; Walker, M.

    2016-01-01

    Phobos, the innermost satellite of Mars, displays an extensive system of grooves that are mostly symmetric about its sub-Mars point. Phobos is steadily spiraling inward due to the tides it raises on Mars lagging behind Phobos' orbital position and will suffer tidal disruption before colliding with Mars in a few tens of millions of years. We calculate the surface stress field of the deorbiting satellite and show that the first signs of tidal disruption are already present on its surface. Most of Phobos' prominent grooves have an excellent correlation with computed stress orientations. The model requires a weak interior that has very low rigidity on the tidal evolution time scale, overlain by an approximately 10-100 m exterior shell that has elastic properties similar to lunar regolith as described by Horvath et al. (1980).

  15. Organic geochemistry in Pennsylvanian tidally influenced sediments from SW Indiana

    Science.gov (United States)

    Mastalerz, Maria; Kvale, E.P.; Stankiewicz, B.A.; Portle, K.

    1999-01-01

    Tidal rhythmites are vertically stacked small-scale sedimentary structures that record daily variations in tidal current energy and are known to overlie some low-sulfur coals in the Illinois Basin. Tidal rhythmites from the Pennsylvanian Brazil Formation in Indiana have been analyzed sedimentologically, petrographically, and geochemically in order to understand the character and distribution of organic matter (OM) preserved in an environment of daily interactions between marine and fresh waters. The concentration of organic matter (TOC) ranges from traces to 6.9% and sulfur rarely exceeds 0.1% in individual laminae. Angular vitrinite is the major organic matter type, accounting for 50-90% of total OM. The C/S ratio decreases as the verfical distance from the underlying coal increases. A decreasing C/S ratio coupled with decreases in Pr/Ph, Pr/n-C17, Ph/n-C18 ratios and a shift of carbon isotopic composition towards less negative values suggest an increase in salinity from freshwater in the mudflat tidal rhythmite facies close to the coal to brackish/marine in the sandflat tidal rhythmite facies further above from the coal. Within an interval spanning one year of deposition, TOC and S values show monthly variability. On a daily scale, TOC and S oscillations are still detectable but they are of lower magnitude than on a monthly scale. These small-scale variations are believed to reflect oscillations in water salinity related to tidal cycles.Tidal rhythmites are vertically stacked small-scale sedimentary structures that record daily variations in tidal current energy and are known to overlie some low-sulfur coals in the Illinois Basin. Tidal rhythmites from the Pennsylvanian Brazil Formation in Indiana have been analyzed sedimentologically, petrographically, and geochemically in order to understand the character and distribution of organic matter (OM) preserved in an environment of daily interactions between marine and fresh waters. The concentration of organic matter

  16. Tidal and residual currents in the Bransfield Strait, Antarctica

    Directory of Open Access Journals (Sweden)

    O. López

    Full Text Available During the 1992-1993 oceanographic cruise of the Spanish R/V Hespérides, recording equipment was deployed in the Bransfield Strait. Six Aanderaa RCM7 current meters and three Aanderaa WLR7 tide gauges were successfully recovered after an operation period of 2.5 months. Relevant features of the time series obtained are presented and discussed in this paper. The emphasis is placed on the tidal character of the currents and the relative importance of tidal flow in the general hydrodynamics of the strait. For these purposes a dense grid of hydrographic stations, completed during the BIOANTAR 93 cruise, is used. Preliminary geostrophic calculations relative to a 400 m depth, yield current velocities of around 0.20 m s-1 in the study area, whereas the magnitude of tidal currents is seen to be 0.30-0.40 m s-1.

  17. Simulations of Magnetic Fields in Tidally-Disrupted Stars

    CERN Document Server

    Guillochon, James

    2016-01-01

    We perform the first magnetohydrodynamical simulations of tidal disruptions of stars by supermassive black holes. We consider stars with both tangled and ordered magnetic fields, for both grazing and deeply disruptive encounters. When the star survives disruption, we find its magnetic field amplifies by a factor of up to twenty, but see no evidence for the a self-sustaining dynamo that would yield arbitrary field growth. For stars that do not survive, and within the tidal debris streams produced in partial disruptions, we find that the component of the magnetic field parallel to the direction of stretching along the debris stream only decreases slightly with time, eventually resulting in a stream where the magnetic pressure is in equipartition with the gas. Our results suggest that the returning gas in most (if not all) stellar tidal disruptions is already highly magnetized by the time it returns to the black hole.

  18. TIDAL SHEAR AND THE V1309 SCO MERGER

    Directory of Open Access Journals (Sweden)

    Gloria Koenigsberger

    2016-01-01

    Full Text Available We show that the observed decline in the orbital period of the merger candidate V1309 Sco could have been driven by tidal shear energy dissipation, E˙ S. This mechanism becomes relevant once the expanding layers of an evolving star rotate asynchronously. For a 1 M⊙ + 0 . 8 M⊙ system with orbital period P=1.44 d, we find that E˙ S can power a growth in stellar radius from 1 .50 R ⊙ to 1 .85 R ⊙ in the primary over the course of ≃ 5 years, during which the rate of period change goes from ≃ 1000 yr to ≃ 170 yr, in agreement with the observations. The kinematical viscosity used for these calculations is estimated from the maximum tidal flow speed and from the extension of the the tidal bulge, and is thus a function of the stellar and orbital parameters.

  19. Tidal Dissipation and Obliquity Evolution in Hot Jupiter Systems

    CERN Document Server

    Valsecchi, Francesca

    2014-01-01

    Two formation scenarios have been proposed to explain the tight orbits of hot Jupiters. These giant planets could be formed in low-obliquity orbits via disk migration or in high-obliquity orbits via high-eccentricity migration, where gravitational interactions with a companion are at play, together with tidal dissipation. Here we target the observed misaligned hot Jupiter systems to investigate whether their current properties are consistent with high-eccentricity migration. Specifically, we study whether tidal dissipation in the star can be responsible for the observed distribution of misalignments and orbital separations. Improving on previous studies, we use detailed models for the stellar component, thus accounting for how convection (and thus tidal dissipation) depends on the host star properties. We find that the currently observed degree of misalignment increases as the amount of surface convection in the host star decreases. This trend supports the hypothesis that tides are the mechanism shaping the o...

  20. Time Scales and Tidal Effects in Minor Mergers

    Institute of Scientific and Technical Information of China (English)

    Yu Lu; Jian-Yan Wei

    2003-01-01

    We use controlled N-body simulation to investigate the dynamical processes (dynamical friction, tidal truncation, etc.) involved in the merging of small satellites into bigger halos. We confirm the validity of some analytic formulae proposed earlier based on simple arguments. For rigid satellites represented by softened point masses, the merging time scale depends on both the orbital shape and concentration of the satellite. The dependence on orbital ellipticity is roughly a power law, as suggested by Lacey & Cole, and the dependence on satellite concentration is similar to that proposed by White. When merging satellites are represented by non-rigid objects, Tidal effects must be considered. We found that material beyond the tidal radius are stripped off. The decrease in the satellite mass might mean an increase in the merging time scale, but in fact, the merging time is decreased,because the stripped-off material carries away a proportionately larger amount of of orbital energy and angular momentum.

  1. The Observational Effects and Signatures of Tidally Distorted Solid Exoplanets

    CERN Document Server

    Saxena, Prabal; Summers, Michael

    2014-01-01

    Our work examines the detectability of tidally distorted solid exoplanets in synchronous rotation. Previous work has shown that tidally distorted shapes of close-in gas giants can give rise to radius underestimates and subsequently density overestimates for those planets. We examine the assumption that such an effect is too minimal for rocky exoplanets and find that for smaller M Class stars there may be an observationally significant tidal distortion effect at very close-in orbits. We quantify the effect for different stellar types and planetary properties using some basic assumptions. Finally, we develop a simple analytic expression to test if there are detectable bulge signatures in the photometry of a system. We find that close in for smaller M Class stars there may be an observationally significant signature that may manifest itself in both in-transit bulge signatures and ellipsoidal variations.

  2. Tidal instability in a rotating and differentially heated ellipsoidal shell

    CERN Document Server

    Cébron, David; Bars, Michael Le; 10.1111/j.1365-246X.2010.04712.x

    2010-01-01

    The stability of a rotating flow in a triaxial ellipsoidal shell with an imposed temperature difference between inner and outer boundaries is studied numerically. We demonstrate that (i) a stable temperature field encourages the tidal instability, (ii) the tidal instability can grow on a convective flow, which confirms its relevance to geo- and astrophysical contexts and (iii) its growth rate decreases when the intensity of convection increases. Simple scaling laws characterizing the evolution of the heat flux based on a competition between viscous and thermal boundary layers are derived analytically and verified numerically. Our results confirm that thermal and tidal effects have to be simultaneously taken into account when studying geophysical and astrophysical flows.

  3. Satellite tidal magnetic signals constrain oceanic lithosphere-asthenosphere boundary

    DEFF Research Database (Denmark)

    Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.

    2016-01-01

    The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation ofsecondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; however......, there are no reports that these signals have been used to infer subsurface structure. We use satellite-detected tidal magnetic fields to image the global electrical structure of the oceanic lithosphere and upper mantle down to a depth of about 250 km. Themodel derived from more than 12 years of satellite data reveals...... a ≈72-km-thick upper resistive layer followed by a sharp increase in electrical conductivity likely associated with the lithosphere-asthenosphere boundary, which separates colder rigid oceanic plates from the ductile and hotter asthenosphere....

  4. Approximate Universal Relations among Tidal Parameters for Neutron Star Binaries

    CERN Document Server

    Yagi, Kent

    2016-01-01

    One of largest uncertainties in nuclear physics is the relation between the pressure and density of supranuclear matter: the equation of state. Some of this uncertainty may be removed through future gravitational wave observations of neutron star binaries by extracting the tidal deformabilities (or Love numbers) of neutron stars. Previous studies showed that only a certain combination of the individual deformabilities of each body (chirp tidal deformability) can be measured with second-generation gravitational wave interferometers, such as Adv. LIGO, due to correlations between the individual deformabilities. To overcome this, we search for approximately universal (or equation-of-state independent) relations between two combinations of the individual tidal deformabilities, such that once one of them has been measured, the other can be automatically obtained and the individual ones decoupled through these relations. We find an approximately universal relation between the symmetric and the anti-symmetric combin...

  5. Three-dimensional semi-idealized model for tidal motion in tidal estuaries. An application to the Ems estuary

    Science.gov (United States)

    Kumar, Mohit; Schuttelaars, Henk M.; Roos, Pieter C.; Möller, Matthias

    2016-01-01

    In this paper, a three-dimensional semi-idealized model for tidal motion in a tidal estuary of arbitrary shape and bathymetry is presented. This model aims at bridging the gap between idealized and complex models. The vertical profiles of the velocities are obtained analytically in terms of the first-order and the second-order partial derivatives of surface elevation, which itself follows from an elliptic partial differential equation. The surface elevation is computed numerically using the finite element method and its partial derivatives are obtained using various methods. The newly developed semi-idealized model allows for a systematic investigation of the influence of geometry and bathymetry on the tidal motion which was not possible in previously developed idealized models. The new model also retains the flexibility and computational efficiency of previous idealized models, essential for sensitivity analysis. As a first step, the accuracy of the semi-idealized model is investigated. To this end, an extensive comparison is made between the model results of the semi-idealized model and two other idealized models: a width-averaged model and a three-dimensional idealized model. Finally, the semi-idealized model is used to understand the influence of local geometrical effects on the tidal motion in the Ems estuary. The model shows that local convergence and meandering effects can have a significant influence on the tidal motion. Finally, the model is applied to the Ems estuary. The model results agree well with observations and results from a complex numerical model.

  6. Observations and modeling of a tidal inlet dye tracer plume

    Science.gov (United States)

    Feddersen, Falk; Olabarrieta, Maitane; Guza, R. T.; Winters, D.; Raubenheimer, Britt; Elgar, Steve

    2016-10-01

    A 9 km long tracer plume was created by continuously releasing Rhodamine WT dye for 2.2 h during ebb tide within the southern edge of the main tidal channel at New River Inlet, NC on 7 May 2012, with highly obliquely incident waves and alongshore winds. Over 6 h from release, COAWST (coupled ROMS and SWAN, including wave, wind, and tidal forcing) modeled dye compares well with (aerial hyperspectral and in situ) observed dye concentration. Dye first was transported rapidly seaward along the main channel and partially advected across the ebb-tidal shoal until reaching the offshore edge of the shoal. Dye did not eject offshore in an ebb-tidal jet because the obliquely incident breaking waves retarded the inlet-mouth ebb-tidal flow and forced currents along the ebb shoal. The dye plume largely was confined to <4 m depth. Dye was then transported downcoast in the narrow (few 100 m wide) surfzone of the beach bordering the inlet at 0.3 m s-1 driven by wave breaking. Over 6 h, the dye plume is not significantly affected by buoyancy. Observed dye mass balances close indicating all released dye is accounted for. Modeled and observed dye behaviors are qualitatively similar. The model simulates well the evolution of the dye center of mass, lateral spreading, surface area, and maximum concentration, as well as regional ("inlet" and "ocean") dye mass balances. This indicates that the model represents well the dynamics of the ebb-tidal dye plume. Details of the dye transport pathways across the ebb shoal are modeled poorly perhaps owing to low-resolution and smoothed model bathymetry. Wave forcing effects have a large impact on the dye transport.

  7. Late Miocene Tidal Deposits in the Amazonian Foreland Basin

    Science.gov (United States)

    Rasanen, Matti E.; Linna, Ari M.; Santos, Jose C. R.; Negri, Francisco R.

    1995-07-01

    Late Miocene tidal sediments of Acre, Brazilian Amazonia, were deposited in an embayment or interior seaway located in the sub-Andean zone. This late Tertiary embayment system may once have connected the Caribbean with the South Atlantic. The tidal coasts of the embayment-seaway have provided an avenue for the earliest waif (over water) dispersal phases of the great American biotic interchange in the late Miocene. The subsequent change from semimarine to terrestrial environments is of value in assessing the importance of earlier hypotheses on the evolution of the western Amazonian landscape and gives insight into the formation of several observed biogeographic patterns, especially of aquatic biota.

  8. Research on Local Scour at Bridge Pier under Tidal Action

    Directory of Open Access Journals (Sweden)

    Wang Jianping

    2015-01-01

    Full Text Available Through the local scour test at bridge pier under tidal action in a long time series, this paper observes the growing trend of the deepest point of local scour at bridge pier under tidal conditions with different characteristic parameters, analyzes the impact of repeat sediment erosion and deposition in the scouring pit caused by reversing current on the development process of the scouring pit, and clarifies the relation between the tide and local scouring depth at bridge pier under steady flow conditions, so as to provide a scientific basis for bridge design and safe operation of estuary and harbor areas.

  9. Identification of the Opportunities for Future Development of Tidal Energy

    Directory of Open Access Journals (Sweden)

    Navid Bozorgan

    2015-09-01

    Full Text Available An overview of status of development of tidal energy is given in this article. To reduce the dependance on fossil fuel and imported energy resources, the need for ocean energy is a global demand in developing countries. The ability to directly extract from the world’s oceans may be in the form of mechanical energy from waves, tides, or currents, or in the form of thermal energy from the sun’s heat. This paper identifies the opportunities for future development of tidal energy.

  10. Tidal Movement of Nioghalvfjerdsfjorden Glacier, Northeast Greenland: Observations and Modelling

    DEFF Research Database (Denmark)

    Reeh, Niels; Mayer, C.; Olesen, O. B.;

    2000-01-01

    , 1997 and 1998. As part of this work, tidal-movement observations were carried out by simultaneous differential global positioning system (GPS) measurements at several locations distributed on the glacier surface. The GPS observations were performed continuously over several tidal cycles. At the same...... time, tiltmeter measurements were carried out in the grounding zones along the glacier margins and upstream, where the glacier leaves the main ice sheet. A tide gauge installed in the sea immediately in front of the glacier front recorded the tide in the open sea during the field seasons...

  11. Perpetual long libration of terrestrial planets in tidal resonances

    Science.gov (United States)

    Makarov, Valeri

    2015-11-01

    On the example of Mercury, I show that firm planets of terrestrial composition, locked in the 3:2 or higher spin-orbit resonances, undergo long-period perpetual libration in longitude without any influence of third bodies. This non-damped libration at the natural frequency is driven by a secular tidal torque, which is increasing with frequency within a narrow interval around the resonance. The spectrum of regular forced, eccentricity-driven, libration defines the conditions for the perpetual long libration. The possibility of validating the tidal theory from the observable amplitude of perpetual libration is discussed.

  12. Balance of assimilative and dissimilative nitrogen processes in a diatom-rich tidal flat sediment

    Directory of Open Access Journals (Sweden)

    K. Dähnke

    2012-10-01

    Full Text Available Tidal flat sediments are subject to repetitive mixing and resuspension events. In a short-term (24 h 15N-labelling experiment, we investigated reactive nitrogen cycling in a tidal flat sediment following an experimentally induced resuspension event. We focused on (a the relative importance of assimilatory versus dissimilatory processes and (b the role of benthic microalgae therein. 15N-labelled substrate was added to homogenized sediment, and 15N was subsequently traced into sediment and dissolved inorganic nitrogen (DIN pools. Integration of results in a N-cycle model allowed us to quantify the proportion of major assimilatory and dissimilatory processes in the sediment.

    Upon sediment disturbance, rates of dissimilatory processes like nitrification and denitrification were very high, but declined rapidly towards a steady state. Once this was reached, the balance between assimilation and dissimilation in this tidal mudflat was mainly dependent on the nitrogen source: nitrate was utilized almost exclusively dissimilatory via denitrification, whereas ammonium was rapidly assimilated, with about a quarter of this assimilation due to benthic microalgae (BMA. Benthic microalgae significantly affected the nitrogen recycling balance in sediments, because in the absence of BMA activity the recovering sediment turned from a net ammonium sink to a net source.

    The driving mechanisms for assimilation or dissimilation accordingly appear to be ruled to a large extent by external physical forcing, with the entire system being capable of rapid shifts following environmental changes. Assimilatory pathways gain importance under stable conditions, with a substantial contribution of BMA to total assimilation.

  13. Assessment of Energy Production Potential from Tidal Streams in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Haas, Kevin A. [Georgia Inst. of Technology, Savannah, GA (United States); Fritz, Hermann M. [Georgia Inst. of Technology, Savannah, GA (United States); French, Steven P. [Georgia Inst. of Technology, Atlanta, GA (United States); Smith, Brennan T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Neary, Vincent [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2011-06-29

    The project documented in this report created a national database of tidal stream energy potential, as well as a GIS tool usable by industry in order to accelerate the market for tidal energy conversion technology.

  14. Collaborative research approaches to cope with uncertainty of water management practices in Tidal areas

    NARCIS (Netherlands)

    Ritzema, H.P.

    2013-01-01

    Throughout the world, tidal areas are being developed. The initial development is generally for agriculture, often in combination with flood protection. The development focus in tidal areas is, however, gradually moving to ports, harbours, transportation routes, industries, and aquaculture, housing

  15. Constraining the equation of state of nuclear matter with gravitational wave observations: tidal deformability and tidal disruption

    CERN Document Server

    Maselli, Andrea; Ferrari, Valeria

    2013-01-01

    We study how to extract information on the neutron star equation of state from the gravitational wave signal emitted during the coalescence of a binary system composed by two neutron stars or a neutron star and a black hole. We use Post-Newtonian templates which include the tidal deformability parameter and, when tidal disruption occurs before merger, a frequency cut-off. Assuming that this signal is detected by Advanced LIGO/Virgo or ET, we evaluate the uncertainties on these parameters using different data analysis strategies based on the Fisher matrix approach, and on recently obtained analytical fits of the relevant quantities. We find that the tidal deformability is more effective than the stellar compactness to discriminate among different possible equations of state.

  16. Effect of high tidal volume ventilation and lipopolysaccharide on mitogen-activated protein kinase in rat lung tissue

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Mechanical ventilation, a crucial therapy to acute respiratory distress syndrome (ARDS), could exacerbate lung injury, and even result in ventilator-induced lung injury (VILI) if misused in some condition1. Over-activating inflammatory cells and expanding inflammatory responses, which are induced by infection, are fundamental reasons for ARDS. Among them, mitogen-activated protein kinase (MAPK) intracellular signal transduction pathways are key processes. This study aimed to investigate the time course of MAPK activation in rat lung tissue after high tidal volume (VT) ventilation and the role of lipopolysaccharide (LPS) in high-sensitivity, and to elucidate the effect of the pathway on VILI.

  17. Tidal-Fluvial and Estuarine Processes in the Lower Columbia River: I. Along-channel Water Level Variations, Pacific Ocean to Bonneville Dam

    Energy Technology Data Exchange (ETDEWEB)

    Jay, D. A.; Leffler, K.; Diefenderfer, Heida L.; Borde, Amy B.

    2015-03-01

    This two-part paper provides comprehensive time and frequency domain analyses and models of along-channel water level variations in the 234km-long Lower Columbia River and Estuary (LCRE) and documents the response of floodplain wetlands thereto. In Part I, power spectra, continuous wavelet transforms, and harmonic analyses are used to understand the influences of tides, river flow, upwelling and downwelling, and hydropower operations ("power-peaking") on the water level regime. Estuarine water levels are influenced primarily by astronomical tides and coastal processes, and secondarily by river flow. The importance of coastal and tidal influences decreases in the landward direction, and water levels are increasingly controlled by river flow variations at periods from ≤1 day to years. Water level records are only slightly non-stationary near the ocean, but become increasingly irregular upriver. Although astronomically forced tidal constituents decrease above the estuary, tidal fortnightly and overtide variations increase for 80-200km landward, both relative to major tidal constituents and in absolute terms.

  18. Tidal and sub-tidal sea level variability at the northern shelf of the Brazilian Northeast Region

    Directory of Open Access Journals (Sweden)

    FELIPE F. FROTA

    2016-01-01

    Full Text Available ABSTRACT A characterization of the sea level variability at tidal and sub-tidal frequencies at the northern shore of the Brazilian Northeast shelf for the period 2009-2011 is presented. The sea level data used was obtained from the Permanent Geodetic Tide Network from the Brazilian Institute of Geography and Statistics for the Fortaleza gauge station. Local wind data was also used to assess its effects on the low-frequency sea level variability. The variability of the sea level was investigated by classical harmonic analysis and by morphology assessment over the tidal signal. The low frequencies were obtained by low-pass filtering. The tidal range oscillated with the highest value of 3.3 m during the equinox and the lowest value of 0.7 m during the solstice. Differences between the spring and neap tides were as high as 1 m. A total of 59 tidal constituents were obtained from harmonic analysis, and the regional tide was classified as semi-diurnal pure with a form number of 0.11. An assessment of the monthly variability of the main tidal constituents (M2, S2, N2, O1, and K1 indicated that the main semi-diurnal solar S2 presented the highest variability, ranging from 0.21 to 0.41 m; it was the main element altering the form number through the years. The low frequency sea-level variability is negligible, although there is a persistent signal with an energy peak in the 10-15 day period, and it cannot be explained by the effects of local winds.

  19. 呼气末二氧化碳分压的变化对感染性休克机械通气患者容量反应性的预测价值%The value of changes in end-tidal carbon dioxide pressure induced by passive leg raising test in predicting fluid responsiveness in mechanically ventilated patients with septic shock

    Institute of Scientific and Technical Information of China (English)

    臧芝栋; 严洁; 许红阳; 梁锋鸣; 杨挺; 王大鹏; 高飞

    2013-01-01

    Objective To test whether the changes of partial end-tidal carbon dioxide pressure (PETCO2) during passive leg raising (PLR) predict fluid responsiveness in mechanically ventilated patients with septic shock.Methods Forty-two mechanically ventilated patients with septic shock admitted from January 2012 to November 2012 were prospectively recruited.Hemodynamic parameters monitored by a pulse indicator continuous cardiac output(PiCCO) device and PETCO2 monitored by an expiratory-CO2 device were studied at baseline,after PLR,and after volume expansion.Fluid responsiveness was defined as an increase in cardiac index (CI) of 15% or greater after volume expansion.The correlation between PLR-induced CI change (△CIPLR) and PETCO2 (△PETCO2-PLR) was analyzed.The value of △PETCO2-PLR to predict fluid responsiveness was evaluated by receiver operating characteristic (ROC) curves.Results A total of 42 patients were enrolled in this study,of whom,24 had a CI increase of ≥ 15% after volume expansion (responders).After PLR,CI and PETCO2 were both significantly increased in the response group compared with baseline [(21.4 ± 12.9) % of CI and (9.6 ± 4.7) % of PETCO2,P < 0.05],while no significant changes were observed (P > 0.05) in the non-response group.Both △CIPLR and △PETCO2-PLR were significantly higher in responder group than in the non-responder group (both P < 0.05).△CI and △PETCO2 after PLR were strongly correlated (r =0.64,P < 0.05).In responders after PLR,the area under ROC curve of △PETCO2-PLR was 0.900 ± 0.056 (95% CI 0.775-1.000,P < 0.05).An increase of ≥ 5% in △PETCO2-PLR predicted fluid responsiveness with a sensitivity of 88.0% and specificity of 88.2%.Conclusions The change of PETCO2 induced by passive leg raising is a non-invasive and easy way to predict fluid responsiveness in mechanically ventilated patients with septic shock.%目的 探讨呼气末二氧化碳分压(PETCO2)在被动抬腿试验中的变化及

  20. Anelasticity across seismic to tidal timescales: a self-consistent approach

    Science.gov (United States)

    Lau, Harriet C. P.; Faul, Ulrich; Mitrovica, Jerry X.; Al-Attar, David; Tromp, Jeroen; Garapić, Gordana

    2017-01-01

    In a pioneering study, Wahr & Bergen developed the widely adopted, pseudo-normal mode framework for predicting the impact of anelastic effects on the Earth's body tides. Lau et al. have recently derived an extended normal mode treatment of the problem (as well as a minor variant of the theory known as the direct solution method) that makes full use of theoretical developments in free oscillation seismology spanning the last quarter century and that avoids a series of assumptions and approximations adopted in the traditional theory for predicting anelastic effects. There are two noteworthy differences between these two theories: (1) the traditional theory only considers perturbations to the eigenmodes of an elastic Earth, whereas the new theory augments this set of modes to include the relaxation modes that arise in anelastic behaviour; and (2) the traditional theory approximates the complex perturbation to the tidal Love number as a scaled version of the complex perturbation to the elastic moduli, whereas the new theory computes the full complex perturbation to each eigenmode. In this study, we highlight the above differences using a series of synthetic calculations, and demonstrate that the traditional theory can introduce significant error in predictions of the complex perturbation to the Love numbers due to anelasticity and the related predictions of tidal lag angles. For the simplified Earth models we adopt, the computed lag angles differ by ˜20 per cent. The assumptions in the traditional theory have important implications for previous studies that use model predictions to correct observables for body tide signals or that analyse observations of body tide deformation to infer mantle anelastic structure. Finally, we also highlight the fundamental difference between apparent attenuation (i.e. attenuation inferred from observations or predicted using the above theories) and intrinsic attenuation (i.e. the material property investigated through experiments

  1. SNL-EFDC Simulations of Tidal Turbine-Related Changes to Hydrodynamics and Flushing

    Science.gov (United States)

    Roberts, J. D.; Johnson, E.; James, S. C.; Barco, J.; Jones, C.

    2012-12-01

    The marine and hydrokinetic (MHK) industry in the United States faces challenges associated with siting, permitting, construction, and operation of pilot- and full-scale facilities that must be addressed to accelerate environmentally sound deployment of these renewable energy technologies. Little is known about the potential effects of MHK device operation in coastal areas, estuaries, or rivers, or of the cumulative impacts of these devices on aquatic ecosystems. This lack of knowledge affects the actions of regulatory agencies, the opinions of stakeholder groups, and the commitment of energy project developers and investors. Two particularly important factors that can be used as a precursor for MHK-driven environmental changes in estuaries are the effect of decreased tidal range and flushing. For example, tidal-range changes could affect wetland systems that are only wetted under the highest of tides. Significant changes in tidal range could completely change the character of the wetlands through long-term drying. Changes to flushing must also be understood, especially when municipal wastewater and other pollutant sources are discharged into a bay. When MHK operation alters flow rates, decreased flushing of an embayment could yield increased residence times, decreased nutrient and contaminant dispersion, and even the possibility of algal blooms. Small changes to the flow could manifest as noticeable changes to sediment transport and water quality. This work provides example assessments of changes to the physical environment (i.e. currents, tidal ranges, water age, and e-folding time) potentially imposed by the operation of MHK turbine arrays in marine estuary environments using the modeling platform SNL-EFDC. Comparing model results with and without an MHK array facilitates an understanding of how an array of turbines might alter the environment. By using models to simulate water circulation, commensurate changes in water quality, benthic habitat quality, and

  2. VCC 2062: an old Tidal Dwarf Galaxy in the Virgo Cluster?

    CERN Document Server

    Duc, Pierre-Alain; Lisenfeld, Ute; Brinks, Elias; Boquien, Mederic

    2007-01-01

    Numerical simulations predict the existence of old Tidal Dwarf Galaxies (TDGs) that would have survived several Gyr after the collision lying at their origin. Such survivors, which would by now have become independent relaxed galaxies, would be ideal laboratories, if nearby enough, to tackle a number of topical issues, including the distribution of Dark Matter in and around galaxies. However finding old dwarf galaxies with a confirmed tidal origin is an observational challenge. A dwarf galaxy in the Virgo Cluster, VCC 2062, exhibits several unusual properties that are typical of a galaxy made out of recycled material. We discuss whether it may indeed be a TDG. We analysed multi-wavelength observations of VCC 2062, including an IRAM CO map, an optical spectrum of its HII regions, GALEX ultraviolet and archival broad-band and narrow-band optical images as well as a VLA HI datacube, originally obtained as part of the VIVA project. VCC 2062 appears to be the optical, low surface brightness counterpart of a kinema...

  3. Tidal modulation of temperature oscillations monitored in borehole Yaxcopoil-1 (Yucatán, Mexico)

    Science.gov (United States)

    Cermak, Vladimir; Bodri, Louise; Safanda, Jan

    2009-05-01

    For better understanding of temperature state in the subsurface, temperature-depth logs can be suitably completed by high-resolution long-run temperature-time monitoring at selected depths. The results of temperature monitoring at three depth levels in borehole Yaxcopoil-1, Chicxulub impact structure, Mexico (April/May 2006) proved that even when a borehole is in "fully" stabilized conditions, temperature may exhibit certain unrest resembling irregular oscillations in the order of hundredths or (in the extreme case) even first tenths of degree. Two novel methods for detection of the weak fingerprints of stable periodic components in long noisy records, namely the RQI (Recurrence Quantification Interval) analysis and the HiCum (Histograms Cumulation) were used to isolate the constituents with tidal periodicities from temperature oscillations measured in borehole Yaxcopoil-1. Both analyses revealed that temperature series contain perceptible tidal component. The field data were correlated with the simulated synthetic tides. The comparison of staked HiCum records for the theoretical gravity tide and monitored temperature shows significant positive linear correlation between both variables. There is a small lag between two signals corresponding to ~ 25 min phase difference.

  4. Predictions for the detection of Tidal Streams with Gaia using Great Circle Methods

    CERN Document Server

    Mateu, Cecilia; Font, Andreea S; Aguilar, Luis; Frenk, Carlos; Cole, Shaun; Wang, Wenting; McCarthy, Ian G

    2016-01-01

    The Gaia astrometric mission may offer an unprecedented opportunity to discover new tidal streams in the Galactic halo. To test this, we apply nGC3, a great-circle-cell count method that combines position and proper motion data to identify streams, to eleven mock Gaia catalogues of K giants and RR Lyrae stars constructed from cosmological simulations of Milky Way analogues. We analyse two sets of simulations, one using a combination of N-body and semi-analytical methods which has extremely high resolution, the other using hydro-dynamical methods, which captures the dynamics of baryons, including the formation of an in situ halo. These eleven realizations of plausible Galactic merger histories allow us to assess the potential for the recovery of tidal streams in different Milky Way formation scenarios. We include the Gaia selection function and observational errors in these mock catalogues. We find that the nGC3 method has a well-defined detection boundary in the space of stream width and projected overdensity...

  5. Assessment of the climate change impacts on fecal coliform contamination in a tidal estuarine system.

    Science.gov (United States)

    Liu, Wen-Cheng; Chan, Wen-Ting

    2015-12-01

    Climate change is one of the key factors affecting the future microbiological water quality in rivers and tidal estuaries. A coupled 3D hydrodynamic and fecal coliform transport model was developed and applied to the Danshuei River estuarine system for predicting the influences of climate change on microbiological water quality. The hydrodynamic and fecal coliform model was validated using observational salinity and fecal coliform distributions. According to the analyses of the statistical error, predictions of the salinity and the fecal coliform concentration from the model simulation quantitatively agreed with the observed data. The validated model was then applied to predict the fecal coliform contamination as a result of climate change, including the change of freshwater discharge and the sea level rise. We found that the reduction of freshwater discharge under climate change scenarios resulted in an increase in the fecal coliform concentration. The sea level rise would decrease fecal coliform distributions because both the water level and the water volume increased. A reduction in freshwater discharge has a negative impact on the fecal coliform concentration, whereas a rising sea level has a positive influence on the fecal coliform contamination. An appropriate strategy for the effective microbiological management in tidal estuaries is required to reveal the persistent trends of climate in the future.

  6. Tidal Influence on Nutrients Status and Phytoplankton Population of Okpoka Creek, Upper Bonny Estuary, Nigeria

    Directory of Open Access Journals (Sweden)

    O. A. Davies

    2013-01-01

    Full Text Available Okpoka Creek of the Upper Bonny Estuary in the Niger Delta is a tidal creek receiving organic anthropogenic effluents from its environs. The study investigated the influence of tides (low and high on the species composition, diversity, abundance, and distribution of phytoplankton. The surface water and phytoplankton samples were collected monthly from May 2004 to April 2006 at both tides from ten stations according to standard methods. Phytoplankton was identified microscopically. Species diversity was calculated using standard indices. Data analyses were done using analysis of variance, Duncan multiple range, and descriptive statistics. Phosphate and ammonia exceeded international acceptable levels of 0.10 mg/L for natural water bodies indicating high nutrient status, organic matter, and potential pollutants. A total of 158 species of phytoplankton were identified. Diatoms dominated the phytoplankton (62.9%. Diversity indices of diatoms were 1.5±0.03 (Margalef and 0.8±0.01 (Shannon. Pollution-indicator species such as Navicula microcephala, Nitzschia sigma, Synedra ulna (diatoms, Cladophora glomerata (green alga, Euglena acus (euglenoid, Anabeana spiroides (blue-green alga, and Ceratium furca (dinoflagellate were recorded at either only low, high or both tides. Concerted environmental surveillance on Upper Bonny Estuary is advocated to reduce the inflow of pollutants from the Bonny Estuary into this Creek caused by tidal influence.

  7. Tidal streams in newly discovered M32 analogues: evidence for the stripping scenario

    CERN Document Server

    Huxor, Avon; Price, James; Harniman, Rob

    2011-01-01

    We present two newly-discovered compact elliptical (cE) galaxies, exhibiting clear evidence of tidal steams, and found during a search of SDSS DR7 for cE candidates. The structural parameters of the cEs are derived using GALFIT, giving effective radii, Re, of 388 and 263 parsecs, and B-band mean surface brightnesses within Re of 19.4 and 19.2 magnitudes per arcsec squared. We have re-analysed the SDSS spectra, which indicate that they possess young to intermediate-age stellar populations. These two cEs provide direct evidence, a "smoking gun", for the process of tidal stripping that is believed to be the origin of M32-type galaxies. Both are in small groups with a large spiral fraction, suggesting that we may be seeing the formation of such cE galaxies in dynamically young environments. The more compact of the galaxies is found in a small group not unlike the Local Group, and thus provides an additional model for understanding M32.

  8. Spatially resolved analyses of uranium species using a coupled system made up of confocal laser-scanning microscopy (CLSM) and laser induced fluorescence spectroscopy (LIFS); Ortsaufgeloeste Analyse von Uranspezies mittels einem Gekoppelten System aus Konfokaler Laser-Scanning Mikroskopie (CLSM) und Laser Induzierter Fluoreszenzspektroskopie (LIFS)

    Energy Technology Data Exchange (ETDEWEB)

    Brockmann, S. [Verein fuer Kernverfahrenstechnik und Analytik Rossendorf e.V. (VKTA), Dresden (Germany); Grossmann, K.; Arnold, T. [Helmholtz-Zentrum Dresden-Rossendorf e.V. (Germany). Inst. fuer Ressourcenoekologie

    2014-01-15

    The fluorescent properties of uranium when excited by UV light are used increasingly for spectroscope analyses of uranium species within watery samples. Here, alongside the fluorescent properties of the hexavalent oxidation phases, the tetra and pentavalent oxidation phases also play an increasingly important role. The detection of fluorescent emission spectrums on solid and biological samples using (time-resolved) laser induced fluorescence spectroscopy (TRLFS or LIFS respectively) has, however, the disadvantage that no statements regarding the spatial localisation of the uranium can be made. However, particularly in complex, biological samples, such statements on the localisation of the uranium enrichment in the sample are desired, in order to e.g. be able to distinguish between intra and extra-cellular uranium bonds. The fluorescent properties of uranium (VI) compounds and minerals can also be used to detect their localisation within complex samples. So the application of fluorescent microscopic methods represents one possibility to localise and visualise uranium precipitates and enrichments in biological samples, such as biofilms or cells. The confocal laser-scanning microscopy (CLSM) is especially well suited to this purpose. Coupling confocal laser-scanning microscopy (CLSM) with laser induced fluorescence spectroscopy (LIFS) makes it possible to localise and visualise fluorescent signals spatially and three-dimensionally, while at the same time being able to detect spatially resolved, fluorescent-spectroscopic data. This technology is characterised by relatively low detection limits from up to 1.10{sup -6} M for uranium (VI) compounds within the confocal volume. (orig.)

  9. Understanding relationships between morphology and ecosystem structure in a shallow tidal basins of Venice lagoon

    Science.gov (United States)

    Giuseppina Persichillo, Maria; Taramelli, Andrea; Valentini, Emiliana; Filipponi, Federico; Meisina, Claudia; Zucca, Francesco

    2014-05-01

    Coastal wetlands represent complex ecosystems prone to continue fluctuation of their internal equilibrium. They are valuable natural resources characterized by the continue interactions between geomorphological and biological components. Their adaptation to changing conditions is highly dependent on the rate and extent of spatial and temporal processes and their responses are still poorly understood. According to this, the vulnerability assessment to natural and human made hazard have became fundamental to analyse the resilience of these areas, their ability to cope with the impacts from externally driven forces or the efforts needed to minimize the impacts (Gitay et al., 2011). The objective of this research is to develop a comprehensive and replicable method through the application of Multi-Source data analysis, based on the integration of Earth Observation data and field survey, to analyse a shallow tidal basin of salt marshes, located in the northern part of the Venice lagoon. The study site is characterised by relatively elevated areas colonized by halophytic vegetation, and tidal flats, with not vegetated areas, characterized by lower elevations. Sub-pixel processing techniques (Spectral Mixing Analysis - SMA) were used to analyse the spatial distribution of both vegetation and sediments typology. Furthermore the classifications were assayed in terms of spatial (Power law) and temporal (Empirical Orthogonal Functions) patterns, in order to find the main characteristics of the aforementioned spatial trends and their variation over time. The principal aim is to study the spatio-temporal evolution of this coastal wetland area, in order to indentify tipping points, namely thresholds, beyond which the system reaches critical state and the main climatic, hydrodynamic and morphological variables that may influence and increase this behaviour. This research represents a new approach to study the geomorphological processes and to improve the management and

  10. Site Characterization at a Tidal Energy Site in the East River, NY (usa)

    Science.gov (United States)

    Gunawan, B.; Neary, V. S.; Colby, J.

    2012-12-01

    A comprehensive tidal energy site characterization is performed using ADV measurements of instantaneous horizontal current magnitude and direction at the planned hub centerline of a tidal turbine over a two month period, and contributes to the growing data base of tidal energy site hydrodynamic conditions. The temporal variation, mean current statistics, and turbulence of the key tidal hydrodynamic parameters are examined in detail, and compared to estimates from two tidal energy sites in Puget Sound. Tidal hydrodynamic conditions, including mean annual current (at hub height), the speed of extreme gusts (instantaneous horizontal currents acting normal to the rotor plane), and turbulence intensity (as proposed here, relative to a mean current of 2 m s-1) can vary greatly among tidal energy sites. Comparison of hydrodynamic conditions measured in the East River tidal straight in New York City with those reported for two tidal energy sites in Puget Sound indicate differences of mean annual current speeds, difference in the instantaneous current speeds of extreme gusts, and differences in turbulence intensities. Significant differences in these parameters among the tidal energy sites, and with the tidal resource assessment map, highlight the importance of conducting site resource characterization with ADV measurements at the machine scale. As with the wind industry, which adopted an International Electrotechnical Commission (IEC) wind class standard to aid in the selection of wind turbines for a particular site, it is recommended that the tidal energy industry adopt an appropriate standard for tidal current classes. Such a standard requires a comprehensive field campaign at multiple tidal energy sites that can identify the key hydrodynamic parameters for tidal current site classification, select a list of tidal energy sites that exhibit the range of hydrodynamic conditions that will be encountered, and adopt consistent measurement practices (standards) for site

  11. Ocean tidal loading affecting precise geodetic observations on Greenland: Error account of surface deformations by tidal gravity measurements

    DEFF Research Database (Denmark)

    Jentzsch, G.; Knudsen, Per; Ramatschi, M.

    2000-01-01

    Air-borne and satellite based altimetry are used to monitor the Greenland ice-cap. Since these measurements are related to fiducial sites at the coast, the robustness of the height differences depends on the stability of these reference points. To benefit from the accuracy of these methods...... observations. Near the coast ocean tidal loading causes additional vertical deformations in the order of 1 to 10 cm Therefore, tidal gravity measurements were carried out at four fiducial sites around Greenland in order to provide corrections for the kinematic part of the coordinates of these sites. Starting...

  12. Modeling tidal dynamics in a mangrove creek catchment in Delft3D

    NARCIS (Netherlands)

    Horstman, E.M.; Dohmen-Janssen, C.M.; Hulscher, S.J.M.H.; Bonneton, P.; Garlan, T.

    2013-01-01

    Modeling tidal dynamics in mangroves is of great use in studying the effects of changes in e.g. vegetation cover or tidal forcing. Process based models, taking into account vegetation drag and turbulence, have not yet been applied to study tidal dynamics in mangrove forests. We compare three differe

  13. Diurnal and semi-diurnal tidal currents in the deep mid-Arabian sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S.C.; Gouveia, A.D.; Shetye, S.R.

    Current meter records from two depths, approximately 1000 m, at three mooring in the deep mid-Arabian Sea were used to study tidal components. Tidal ellipses for the semi-diurnal (M2, S2 and K2) and the diurnal (K1 and P1) tidal constituents have...

  14. Passive acoustic methods for fine-scale tracking of harbour porpoises in tidal rapids

    DEFF Research Database (Denmark)

    Macaulay, Jamie; Gordon, Jonathan; Gillespie, Douglas

    2017-01-01

    on how marine mammals use tidal rapid habitats and in particular, their underwater movements and dive behaviour is required. Porpoises, which are the most abundant small cetacean at most European tidal sites, are difficult animals to tag, and the limited size of tidal habitats means that any telemetered...

  15. Tidal residual current and its role in the mean flow on the Changjiang Bank

    Energy Technology Data Exchange (ETDEWEB)

    Xuan, Jiliang; Yang, Zhaoqing; Huang, Daji; Wang, Taiping; Zhou, Feng

    2016-02-01

    Tidal residual current may play an important role in the mean flow in the Changjiang Bank region, in addition to other residual currents, such as the Taiwan Warm Current, the Yellow Sea Coastal Current, and the Yellow Sea Warm Current. In this paper, a detailed structure of the tidal residual current, in particular the meso-scale eddies, in the Changjiang Bank region is observed from model simulations, and its role in the mean flow is quantified using the well-validated Finite Volume Coastal Ocean Model). The tidal residual current in the Changjiang Bank region consists of two components: an anticyclonic regional-scale tidal residual circulation around the edge of the Changjiang Bank and some cyclonic meso-scale tidal residual eddies across the Changjiang Bank. The meso-scale tidal residual eddies occur across the Changjiang Bank and contribute to the regional-scale tidal residual circulation offshore at the northwest boundary and at the northeast edge of the Changjiang Bank, southeastward along the 50 m isobath. Tidal rectification is the major mechanism causing the tidal residual current to flow along the isobaths. Both components of the tidal residual current have significant effects on the mean flow. A comparison between the tidal residual current and the mean flow indicates that the contribution of the tidal residual current to the mean flow is greater than 50%.

  16. Modeling the growth and migration of sandy shoals on ebb-tidal deltas

    NARCIS (Netherlands)

    Ridderinkhof, W.; de Swart, H. E.; van der Vegt, M.; Hoekstra, P.

    2016-01-01

    Coherent sandy shoals that migrate toward the downdrift coast are observed on many ebb-tidal deltas. In this study, processes that cause the growth and migration of shoals on ebb-tidal deltas are identified. Moreover, the effect of the incident wave energy and the tidal prism of an inlet on the migr

  17. Exhaled nitric oxide in healthy young children during tidal breathing through a facemask

    DEFF Research Database (Denmark)

    Daniel, Peter F; Klug, Bent; Valerius, Niels H

    2007-01-01

    The aim of this study was to establish reference values and to examine day-to-day and within-day variations of exhaled nitric oxide (eNO) during tidal breathing in healthy children using a newly described method. Exhaled NO was measured on-line and off-line during tidal breathing through a facemask...... tidal breathing in young children....

  18. Laser-Induced Breakdown Spectroscopy to high-resolution analysis of ion distribution in cement-bound solid; Laser-induzierte Breakdown Spektroskopie (LIBS) zur hochaufloesenden Analyse der Ionenverteilung in zementgebundenen Feststoffen

    Energy Technology Data Exchange (ETDEWEB)

    Molkenthin, Andre

    2009-06-03

    The Laser-Induced Breakdown Spectroscopy allows imaging and quantitative analysis of the ion distribution of all relevant elements on the surface of mineral building materials. The measuring system has been characterised by investigations on specimens of hardened cement paste, mortar and concrete. Transport and accumulation processes are visualised. Besides, results are introduced for the peripheral zone close to the surface and the extraction is shown. (orig.) [German] Die Laser-induzierte Breakdown Spektroskopie ermoeglicht eine bildgebende und quantitative Analyse der Ionenverteilung aller massgeblichen Elemente auf mineralischen Baustoffoberflaechen. Das Messsystem wurde durch verfahrenspezifische Untersuchungen an Proben aus Zementstein, -moerteln und Betonen charakterisiert, Transport- und Anlagerungsprozesse wurden visuell dargestellt. Zudem werden Ergebnisse fuer den Ionenhaushalt in der ungestoerten oberflaechenahen Randzone sowie bei deren Auslaugung bzw. Anreicherung vorgestellt.

  19. Simulating tidal turbines with mesh optimisation and RANS turbulence models

    NARCIS (Netherlands)

    Abolghasemi, A.; Piggott, M.D.; Spinneken, J.; Vire, A.; Cotter, C.J.

    2015-01-01

    A versatile numerical model for the simulation of flow past horizontal axis tidal turbines has been developed. Currently most large-scale marine models employed to study marine energy use the shallow water equations and therefore can fail to account for important turbulent physics. The model present

  20. Anomaly Detection Techniques for the Condition Monitoring of Tidal Turbines

    Science.gov (United States)

    2014-09-29

    a wind turbine, its drive train consists of a gearbox connected to an induction generator, translating tidal speeds of around 3.5 m/s to rotations...Philadelphia, Pa: Temple University BIOGRAPHIES Grant S. Galloway is a PhD student within the Institute for Energy and Environment at the University

  1. Paolo Sarpi and the first Copernican tidal theory.

    Science.gov (United States)

    Naylor, Ron

    2014-12-01

    Despite his demanding religious responsibilities, Paolo Sarpi maintained an active involvement in science between 1578 and 1598- as his Pensieri reveal. They show that from 1585 onwards he studied the Copernican theory and recorded arguments in its favour. The fact that for 1595 they include an outline of a Copernican tidal theory resembling Galileo's Dialogue theory is well known. But examined closely, Sarpi's theory is found to be different from that of the Dialogue in several important respects. That Sarpi was a Copernican by 1592 is revealed by other of his pensieri, whereas at that time we know that Galileo was not. The examination of Sarpi's tidal theory and of the work of Galileo in this period indicates that the theory Sarpi recorded in 1595 was of his own creation. The appreciation that the theory was Sarpi's and that Galileo subsequently came to change his views on the Copernican theory and adopted the tidal theory has major implications for our understanding of the significance of Sarpi's contribution to the Scientific Revolution. Moreover, it appears that several of the most significant theoretical features of the tidal theory published by Galileo in the Dialogue - and which proved of lasting value - were in reality Sarpi's.

  2. Energy storage inherent in large tidal turbine farms.

    Science.gov (United States)

    Vennell, Ross; Adcock, Thomas A A

    2014-06-08

    While wind farms have no inherent storage to supply power in calm conditions, this paper demonstrates that large tidal turbine farms in channels have short-term energy storage. This storage lies in the inertia of the oscillating flow and can be used to exceed the previously published upper limit for power production by currents in a tidal channel, while simultaneously maintaining stronger currents. Inertial storage exploits the ability of large farms to manipulate the phase of the oscillating currents by varying the farm's drag coefficient. This work shows that by optimizing how a large farm's drag coefficient varies during the tidal cycle it is possible to have some flexibility about when power is produced. This flexibility can be used in many ways, e.g. producing more power, or to better meet short predictable peaks in demand. This flexibility also allows trading total power production off against meeting peak demand, or mitigating the flow speed reduction owing to power extraction. The effectiveness of inertial storage is governed by the frictional time scale relative to either the duration of a half tidal cycle or the duration of a peak in power demand, thus has greater benefits in larger channels.

  3. Kinematics in galactic tidal tails - A source for Hypervelocity stars?

    CERN Document Server

    Piffl, Tilmann; Steinmetz, Matthias

    2011-01-01

    [abridged] In this work we study in detail the kinematics of tidal debris stars to investigate the implications of the new scenario that the observed sample of Hypervelocity stars could partly originate from a dwarf-host galaxy collision. We use a suite of N-body simulations following the encounter of a satellite galaxy with its Milky Way-type host galaxy to gather statistics on the properties of stripped-off stars. We study especially the orbital energy distribution of this population. We quantify the typical pattern in angular and phase space formed by the debris stars. We further develop a simple stripping model predicting the kinematics of stripped-off stars. We show that the distribution of orbital energies in the tidal debris has a typical form which can be described quite accurately by a simple function. Based on this we develop a method to predict the energy distribution which allows us to evaluate the significance and the implications of high velocity stars in satellite tidal debris. Generally tidal ...

  4. Investigation of Tidal Power, Cobscook Bay, Maine. Environmental Appendix.

    Science.gov (United States)

    1980-08-01

    Tidal Power Benthic invertebrates Intertidal Marine Habitat Hydroelectric Project Aquaculture Terrestrial Birds Eagles Water Quality Finfish Marine...even greater significance to the trophic ecology of the area is production by macroalgae ( seaweeds ) and eelgrass. Zooplankton abundance is...poor market demand. Currently, a small-scale mussel aquaculture project is underway in Cobscook Bay (scallop and oyster culture are also being

  5. Parameter identification in tidal models with uncertain boundaries

    NARCIS (Netherlands)

    Bagchi, Arunabha; Brummelhuis, ten Paul

    1994-01-01

    In this paper we consider a simultaneous state and parameter estimation procedure for tidal models with random inputs, which is formulated as a minimization problem. It is assumed that some model parameters are unknown and that the random noise inputs only act upon the open boundaries. The hyperboli

  6. Dawes Review 7: The Tidal Downsizing Hypothesis of Planet Formation

    Science.gov (United States)

    Nayakshin, Sergei

    2017-01-01

    Tidal Downsizing scenario of planet formation builds on ideas proposed by Gerard Kuiper in 1951. Detailed simulations of self-gravitating discs, gas fragments, dust grain dynamics, and planet evolutionary calculations are summarised here and used to build a predictive population synthesis. A new interpretation of exoplanetary and debris disc data, the Solar System's origins, and the links between planets and brown dwarfs is offered. Tidal Downsizing predicts that presence of debris discs, sub-Neptune mass planets, planets more massive than 5 Jupiter masses and brown dwarfs should not correlate strongly with the metallicity of the host. For gas giants of Saturn to a few Jupiter mass, a strong host star metallicity correlation is predicted only inwards of a few AU from the host. Composition of massive cores is predicted to be dominated by rock rather than ices. Debris discs made by Tidal Downsizing have an innermost edge larger than about 1 au, have smaller total masses and are usually in a dynamically excited state. Planet formation in surprisingly young or very dynamic systems such as HL Tau and Kepler-444 may be a signature of Tidal Downsizing. Open questions and potential weaknesses of the hypothesis are pointed out.

  7. Dynamics of tidally captured planets in the Galactic Center

    CERN Document Server

    Trani, Alessandro; Spera, Mario; Bressan, Alessandro

    2016-01-01

    Recent observations suggest ongoing planet formation in the innermost parsec of the Galactic center (GC). The super-massive black hole (SMBH) might strip planets or planetary embryos from their parent star, bringing them close enough to be tidally disrupted. Photoevaporation by the ultraviolet field of young stars, combined with ongoing tidal disruption, could enhance the near-infrared luminosity of such starless planets, making their detection possible even with current facilities. In this paper, we investigate the chance of planet tidal captures by means of high-accuracy N-body simulations exploiting Mikkola's algorithmic regularization. We consider both planets lying in the clockwise (CW) disk and planets initially bound to the S-stars. We show that tidally captured planets remain on orbits close to those of their parent star. Moreover, the semi-major axis of the planet orbit can be predicted by simple analytic assumptions in the case of prograde orbits. We find that starless planets that were initially bo...

  8. Quantifying tidally driven benthic oxygen exchange across permeable sediments

    DEFF Research Database (Denmark)

    McGinnis, Daniel F.; Sommer, Stefan; Lorke, Andreas

    2014-01-01

    of permeable sediments and has been identified as increasingly at risk for developing hypoxia. Therefore, we investigate the benthic O-2 exchange across the permeable North Sea sediments using a combination of in situ microprofiles, a benthic chamber, and aquatic eddy correlation. Tidal bottom currents drive...

  9. Tidal dissipation within hot Jupiters: a new appraisal

    CERN Document Server

    Levrard, B; Chabrier, G; Baraffe, I; Selsis, F; Laskar, J; Levrard, Benjamin; Correia, Alexandre Morgado; Chabrier, Gilles; Baraffe, Isabelle; Selsis, Franck; Laskar, Jacques

    2006-01-01

    Eccentricity or obliquity tides have been proposed as the missing energy source that may explain the anomalously large radius of some transiting ``hot Jupiters''. To maintain a non-zero and large obliquity, it was argued that the planets can be locked in a Cassini state, i.e. a resonance between spin and orbital precessions. We compute the tidal heating within ``inflated'' close-in giant planets with a non-zero eccentricity or obliquity. We further inspect whether the spin of a ``hot Jupiter'' could have been trapped and maintained in a Cassini state during its early despinning and migration. We estimate the capture probability in a spin-orbit resonance between $\\sim$ 0.5 AU (a distance where tidal effects become significant) and 0.05 AU for a wide range of secular orbital frequencies and amplitudes of gravitational perturbations. Numerical simulations of the spin evolution are performed to explore the influence of tidal despinning and migration processes on the resonance stability. We find that tidal heating...

  10. Towards Selective Tidal-Stream Transport for Lagrangian profilers

    DEFF Research Database (Denmark)

    Jouffroy, Jerome; Zhou, Qiuyang; Zielinski, Oliver

    2011-01-01

    select and use tidal currents so that a profiler can autonomously reach a desired destination. After presenting the profiler and possible modifications for a coastal environment, we introduce simple mathematical models for the profiler and its environment. We then present a feedback controller that...

  11. Effect of the earth's ellipticity on the lunar tidal potential

    Science.gov (United States)

    Dahlen, F. A.

    1993-01-01

    The earth's orbital acceleration about the moon is influenced by its ellipticity. In this paper it shown that the ellipticity affects tidal gravity by contributing directly to the lunar tide-generating potential (in addition to effecting the elastic-gravitational response of the solid earth and oceans to this potential).

  12. On summer stratification and tidal mixing in the Taiwan Strait

    Institute of Scientific and Technical Information of China (English)

    Jia ZHU; Jianyu HU; Zhiyu LIU

    2013-01-01

    On continental shelves,a front that separates the sea into well-mixed and stratified zones is usually formed in warm seasons due to spatial variations of tidal mixing.In this paper,using eight years of in situ hydrographic observations,satellite images of sea surface temperature (SST) and chlorophyll-a (Chl-a) concentration,and results of a tidal model,we investigate summer stratification in the Taiwan Strait and its dependence on tidal mixing,upwelling,and river diluted water plumes.In most regions of the strait the dominant role of tidal mixing in determining the thermohaline structure is confirmed by the correlation between the two; there are some regions,however,where thermohaline structttre varies in different ways owing to significant influences ofupwelling and river diluted water plumes.The well-mixed regions are mainly distributed on the Taiwan Bank and in the offshore regions offthe Dongshan Island,Nanao Island,and Pingtan Island,while the northern and central Taiwan Strait and the region south of the Taiwan Bank are stratified.The critical Simpson-Hunter parameter for the region is estimated to be 1.78.

  13. Tidal phenomena in reservoirs; Fenomeno de mare em reservatorios

    Energy Technology Data Exchange (ETDEWEB)

    Pinilla Cortes, John Freddy

    1997-06-01

    This work models the oceanic tidal effect on reservoirs by coupling geomechanic principles with equations for fluid in a deformable porous media. The coupling revealed the importance of establishing properly the system compressibility under the various possible configurations of the loading system. The basic models for infinite reservoir, constant outer-pressure reservoir and closed reservoir were considered. It was verified that it was possible to apply the superposition of effects on the solution for the basic models by carrying a simple transformation on the solution variable. The problem was treated by in the context of test analysis, concerning dimensionless form of variables and the inclusion of well effects. The solution for the infinite reservoir including tidal effects. The solution for the infinite reservoir including tidal effects was obtained in the Laplace space and was inverted numerically by using Crump's routine. The results were incorporated to conventional type curves, and were validated by comparison with real and simulated pressure test data. Finally, alternate practices were suggested to integrate the well test analysis in reservoirs affected by the tidal effect. (author)

  14. Numerical Modeling of Tidal Effects in Polytropic Accretion Discs

    Science.gov (United States)

    Godon, P.

    1996-01-01

    A two-dimensional time-dependent hybrid Fourier-Chebyshev method of collocation is developed and used for the study of tidal effects in accretion discs, under the assumption of a polytropic equation of state and a standard alpha viscosity prescription.

  15. Squeezars: Tidally powered stars orbiting a massive black hole

    CERN Document Server

    Alexander, T; Alexander, Tal; Morris, Mark

    2003-01-01

    We propose that there exists a class of transient sources, "squeezars", which are stars caught in highly eccentric orbits around a massive (m<10^8 Mo) black hole (MBH), whose atypically high luminosity (up to a significant fraction of their Eddington luminosity) is powered by tidal interactions with the MBH. Their existence follows from the presence of a mass sink, the MBH, in the galactic center, which drives a flow of stars into nearly radial orbits to replace those it has destroyed. We consider two limits for the stellar response to tidal heating: surface heating with radiative cooling ("hot squeezars") and bulk heating with adiabatic expansion ("cold squeezars"), and calculate the evolution of the squeezar orbit, size, luminosity and effective temperature. The squeezar formation rate is only ~0.05 that of tidal disruption flares, but squeezar lifetimes are many orders of magnitude longer, and so future observations of squeezars in nearby galaxies can probe the tidal process that feeds MBHs and the effe...

  16. Bedform evolution in a tidal inlet referred from wavelet analysis

    DEFF Research Database (Denmark)

    Fraccascia, Serena; Winter, Christian; Ernstsen, Verner Brandbyge;

    2011-01-01

    inlet and evaluate how they changed over consecutive years, when morphology was modified and bedforms migrated. High resolution bathymetric data from the Grådyb tidal inlet channel (Danish Wadden Sea) from seven years from 2002 to 2009 (not in 2004) were analyzed. Continuous wavelet transform of bed...

  17. Production and consumption of biological particles in temperate tidal estuaries

    NARCIS (Netherlands)

    Heip, C.H.R.; Goosen, N.K.; Herman, P.M.J.; Kromkamp, J.C.; Middelburg, J.J.; Soetaert, K.E.R.

    1995-01-01

    The question is reviewed whether a balance exists between production and consumption of biological particles in temperate tidal estuaries and what the relationships are between the magnitude of production and consumption processes and system carbon metabolism. The production terms considered are pri

  18. Jeans Instability in a Tidally Disrupted Halo Satellite Galaxy

    CERN Document Server

    Comparetta, Justin

    2010-01-01

    We use a hybrid test particle/N-body simulation to integrate 4 million massless test particle trajectories within a fully self-consistent 10^5 particle N-body simulation. The number of massless particles allows us to resolve fine structure in the spatial distribution and phase space of a dwarf galaxy as it is disrupted in the tidal field of a Milky Way type galaxy. The tidal tails exhibit nearly periodic clumping or a smoke-like appearance. By running simulations with different satellite particle mass, halo particle mass, number of massive and massless particles and with and without a galaxy disk, we have determined that the instabilities are not due to numerical noise, amplification of structure in the halo, or shocking as the satellite passes through the disk of the Galaxy. We measure Jeans wavelengths and growth timescales in the tidal tail and show that the Jeans instability is a viable explanation for the clumps. We find that the instability causes velocity perturbations of order 10 km/s. Clumps in tidal...

  19. Measuring Ganymede's tidal deformation by laser altimetry: application to the GALA Experiment

    Science.gov (United States)

    Steinbrügge, Gregor; Hussmann, Hauke; Stark, Alexander; Oberst, Jürgen

    2014-05-01

    Measurements of Ganymede's induced magnetic field suggest a salty water layer under the icy crust (Kivelson et al. 2002), in agreement with thermal models based on heat transfer and energy balance equations (e.g., Spohn and Schubert, 2003). Due to the small density contrast between ice-I and liquid water, interior structure models (e.g. Sohl et al. 2003) consistent with Ganymede's moment of inertia and total mass cannot constrain the ice thickness or ocean depth. In order to reduce the ambiguity of the structural models and to constrain the ice thickness, it has been proposed to measure the dynamic response of Ganymede's ice shell to tidal forces exerted by Jupiter characterized by the Love numbers h2 and k2. Similar strategies have been investigated in application to Europa (Wu 2001, Wahr 2006, Hussmann 2011). The body tide Love number h2 depends on the tidal frequency (main tidal cycle is the 7.15 days period of revolution), the internal structure, and the rheology, in particular on the presence of fluid layers, and the thickness and rigidity of an overlaying ice shell. Combined with measurements of the Love number k2, which can be inferred from radio science experiments, and a simultaneous determination of linear combinations of h2 and k2 the obtained data would significantly reduce the ambiguity in structural models (Wahr et al. 2006). A way to determine tidal effects in Ganymede's topography and therefore the h2 value by a spacecraft in orbit is the crossover method: Different orbit tracks will intersect at certain surface locations at different times so that the tidal signal can be extracted from a differential altimetry measurement. The Ganymede Laser Altimeter GALA is one of the instruments selected for the Jupiter Icy Moon Explorer (JUICE). The GALA instrument will perform globally distributed altitude measurements from a low circular orbit. The main challenges for the determination of the tidal amplitude are Ganymede's high surface roughness and low

  20. Observations of ebb flows on tidal flats: Evidence of dewatering?

    Science.gov (United States)

    Rinehimer, J. P.; Thomson, J. M.; Chickadel, C.

    2010-12-01

    Incised channels are a common morphological feature of tidal flats. When the flats are inundated, flows are generally forced by the tidally varying sea surface height. During low tide, however, these channels continue to drain throughout flat exposure even without an upstream source of water. While the role of porewater is generally overlooked due to the low permeability of marine muds, it remains the only potential source of flows through the channels during low tide. In situ and remotely sensed observations (Figure 1) at an incised channel on a tidal flat in Willapa Bay from Spring 2010 indicate that dewatering of the flats may be driving these low tide flows. High resolution Aquadopp ADCP velocity profiles are combined with observations from tower-based infrared (IR) video to produce a complete time series of surface velocity measurements throughout low tide. The IR video observations provide a measurement of surface currents even when the channel depth is below the blanking distance of the ADCP (10 cm). As the depth within the channel drops from 50 cm to 10 cm surface velocities increase from 10 cm/s to 60 cm/s even as the tide level drops below the channel flanks and the flats are dry. As the drainage continues, the temperature of the flow rises throughout low tide, mirroring temperatures within the sediment bed on the tidal flat. Drainage salinity falls despite the lack of any freshwater input to the flat indicating that less saline porewater may be the source. The likely source of the drainage water is from the channel flanks where time-lapse video shows slumping and compaction of channel sediments. Velocity profiles, in situ temperatures, and IR observations also are consistent with the presence of fluid muds and a hyperpycnal, density driven outflow at the channel mouth highlighting a possible pathway for sediment delivery from the flats to the main distributary channels of the bay. Figure 1: Time series of tidal flat channel velocities and temperatures

  1. Identification of the Uncertainties for the Calibration of the Partial Safety Factors for Load in Tidal Turbines

    Directory of Open Access Journals (Sweden)

    Gaizka Zarraonandia Simeón

    2016-03-01

    Full Text Available Tidal energy is nowadays one of the fastest growing types of marine renewable energy. In particular, Horizontal Axis Tidal Turbines (HATTs are the most advanced designs and the most appropriate for standardization. This paper presents a review of actual design criteria focusing on the identification of the uncertainties that technology developers need to address during the design process. Key environmental parameters like turbine inflow conditions or predictions of extreme values are still grey areas due to the lack of site measurements and the uncertainty in metocean model predictions. A comparison of turbulence intensity characterization using different tools and at different points in time shows the uncertainty in the prediction of this parameter. Numerical models of HATTs are still quite uncertain, often dependent on experience of the people running them. In the reliability-based calibration of partial safety factors, the uncertainties need to be reflected on the limit state formulation. This paper analyses the different types of uncertainties present in the limit state equation. These uncertainties are assessed in terms of stochastic variables in the limit state equation. In some cases, advantage can be taken from the experience from offshore wind and oil and gas industries. Tidal turbines have a mixture of the uncertainties present in both industries with regard to partial safety factor calibration.

  2. Motion of a rigid body in a tidal field an application to elliptical galaxies in clusters

    CERN Document Server

    Ciotti, L

    1998-01-01

    We investigate the motion, near the equilibrium configurations, of an initially spinless rigid body subject to an external tidal field. Two cases are considered: when the center of mass of the body is at rest at the equilibrium point of the field generated by a generic mass distribution, and when it is placed on a circular orbit subject to a spherically symmetric potential. A complete analysis of the equilibrium configurations is carried out for both cases. First, we derive the conditions for the stable equilibria, and then we analyze the frequencies of oscillations around the equilibrium positions. In view of these results, we consider the problem of alignment of galaxies in clusters. After estimating the period of the oscillations induced on the galaxies by the tidal field of the cluster, we discuss the possible effect of resonances between stellar orbits inside the galaxy and the oscillations of the galaxy as a whole; this may be a mechanism responsible for producing an intracluster stellar population.

  3. Tidal stirring of satellites with shallow density profiles prevents them from being too big to fail

    CERN Document Server

    Tomozeiu, Mihai; Quinn, Thomas

    2016-01-01

    The "too big to fail" problem is revisited by studying the tidal evolution of populations of dwarf satellites with different density profiles. The high resolution cosmological $\\rm \\Lambda CDM$ "ErisMod" set of simulations is used. These simulations can model both the stellar and dark matter components of the satellites, and their evolution under the action of the tides of a MW-sized host halo at a force resolution better than 10 pc. The stronger tidal mass loss and re-shaping of the mass distribution induced in satellites with $\\gamma=0.6$ dark matter density distributions, as those resulting from the effect of feedback in hydrodynamical simulations of dwarf galaxy formation, is sufficient to bring the circular velocity profiles in agreement with the kinematics of MW's dSphs. In contrast, in simulations in which the satellites retain cusps at $z=0$ there are several "massive failures" with circular velocities in excess of the observational constraints. Various sources of deviations in the conventionally adop...

  4. The number of tidal dwarf satellite galaxies in dependence of bulge index

    CERN Document Server

    Lopez-Corredoira, Martin

    2015-01-01

    We show that a significant correlation (up to 5sigma) emerges between the bulge index, defined to be larger for larger bulge/disk ratio, in spiral galaxies with similar luminosities in the Galaxy Zoo 2 of SDSS and the number of tidal-dwarf galaxies in the catalogue by Kaviraj et al. (2012). In the standard cold or warm dark-matter cosmological models the number of satellite galaxies correlates with the circular velocity of the dark matter host halo. In generalized-gravity models without cold or warm dark matter such a correlation does not exist, because host galaxies cannot capture in-falling dwarf galaxies due to the absence of dark-matter-induced dynamical friction. However, in such models a correlation is expected to exist between the bulge mass and the number of satellite galaxies, because bulges and tidal-dwarf satellite galaxies form in encounters between host galaxies. This is not predicted by dark matter models in which bulge mass and the number of satellites are a priori uncorrelated because higher b...

  5. Salt intrusion in tidal wetlands: European willow species tolerate oligohaline conditions

    Science.gov (United States)

    Markus-Michalczyk, Heike; Hanelt, Dieter; Ludewig, Kristin; Müller, David; Schröter, Brigitte; Jensen, Kai

    2014-01-01

    Tidal wetlands experience salt intrusion due to the effects of climate change. This study clarifies that the European flood plain willows species Salix alba and Salix viminalis tolerate oligohaline conditions. Salix alba L. and Salix viminalis L. are distributed on flood plains up to transitional waters of the oligohaline to the mesohaline estuarine stretch in temperate climates. They experience spatial and temporal variations in flooding and salinity. In the past, willows dominated the vegetation above the mean high water line, attenuated waves and contributed to sedimentation. In recent centuries, human utilization reduced willow stands. Today, the Elbe estuary - a model system for an estuary in temperate zones - exhibits increasing flooding and salinity due to man-induced effects and climatic changes. Willows were described as having no salinity tolerance. In contrast, our soil water salinity measurements at willows in tidal wetlands prove that mature Salix individuals tolerate oligohaline conditions. To assess immature plant salinity tolerance, we conducted a hydroponic greenhouse experiment. Vegetative propagules originating from a freshwater and an oligohaline site were treated in four salinities. Related to growth rates and biomass production, we found interspecific similarities and a salinity tolerance up to salinity 2. Vitality and chlorophyll fluorescence indicated an acclimation of Salix viminalis to oligohaline conditions. We conclude, that the survival of S. alba and S. viminalis and the restoration of willow stands in estuarine flood plains - with regard to wave attenuation and sedimentation - might be possible, despite increasing salinity in times of climate change.

  6. Saturated and Unsaturated Flow due to Tidal Fluctuation and Rainfall in a Coastal Aquifer

    Science.gov (United States)

    Yeh, Hund-Der; Chuang, Mo-Hsiung; Chang, Chia-Hao

    2016-04-01

    The prediction of groundwater level fluctuations due to tidal waves propagation and localized recharge in coastal aquifers is important for the development and management of water resources in coastal areas. Most of the past models for the recharge problem consider either saturated flow or unsaturated flow in the aquifers. However, it is expected that the recharge sources infiltrating from the ground surface have significant impact on the hydraulic heads in saturated and unsaturated zones of an unconfined aquifer in reality. The objective of this study is to derive a closed-form analytical expression for predicting tidal responses in a coastal aquifer system with considering rainfall recharge as well as coupled saturated and unsaturated flow. The model is composed of a linearized Richards equation for unsaturated flow coupled with the saturated groundwater flow equation. The top boundary at the ground surface is represented by the flux condition with a source term denoting the recharge in the coastal aquifer system. The solution of the model is developed in Cartesian coordinates based on the methods of Laplace transform and double-integral transform. On the basis of the analytical solution, the groundwater head fluctuations induced by the joint effect of rainfall and oceanic tides is examined in saturated and unsaturated zones of the aquifer. In addition, the influences of the unsaturated flow on the water table movement are also investigated and discussed. Key words: analytical solution, unsaturated flow, coastal aquifer.

  7. THE NUMBER OF TIDAL DWARF SATELLITE GALAXIES IN DEPENDENCE OF BULGE INDEX

    Energy Technology Data Exchange (ETDEWEB)

    López-Corredoira, Martín [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); Kroupa, Pavel, E-mail: martinlc@iac.es, E-mail: pavel@astro.uni-bonn.de [Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Nussallee 14-16, D-53115 Bonn (Germany)

    2016-01-20

    We show that a significant correlation (up to 5σ) emerges between the bulge index, defined to be larger for a larger bulge/disk ratio, in spiral galaxies with similar luminosities in the Galaxy Zoo 2 of the Sloan Digital Sky Survey and the number of tidal-dwarf galaxies in the catalog by Kaviraj et al. In the standard cold or warm dark matter cosmological models, the number of satellite galaxies correlates with the circular velocity of the dark matter host halo. In generalized gravity models without cold or warm dark matter, such a correlation does not exist, because host galaxies cannot capture infalling dwarf galaxies due to the absence of dark-matter-induced dynamical friction. However, in such models, a correlation is expected to exist between the bulge mass and the number of satellite galaxies because bulges and tidal-dwarf satellite galaxies form in encounters between host galaxies. This is not predicted by dark matter models in which bulge mass and the number of satellites are a priori uncorrelated because higher bulge/disk ratios do not imply higher dark/luminous ratios. Hence, our correlation reproduces the prediction of scenarios without dark matter, whereas an explanation is not found readily from the a priori predictions of the standard scenario with dark matter. Further research is needed to explore whether some application of the standard theory may explain this correlation.

  8. Towards a Low-Cost Modelling System for Optimising the Layout of Tidal Turbine Arrays

    Directory of Open Access Journals (Sweden)

    Stephen Nash

    2015-11-01

    Full Text Available In the long-term, tidal turbines will most likely be deployed in farms/arrays where energy extraction by one turbine may significantly affect the energy available to another turbine. Given the prohibitive cost of experimental and/or field investigations of such turbine interactions, numerical models can play a significant role in determining the optimum layout of tidal turbine arrays with respect to energy capture. In the present research, a low-cost modelling solution for optimising turbine array layouts is presented and assessed. Nesting is used in a far-field model to telescope spatial resolution down to the scale of the turbines within the turbine array, allowing simulation of the interactions between adjacent turbines as well as the hydrodynamic impacts of individual turbines. The turbines are incorporated as momentum sinks. The results show that the model can compute turbine wakes with similar far-field spatial extents and velocity deficits to those measured in published experimental studies. The results show that optimum spacings for multi-row arrays with regard to power yield are 3–4 rotor diameters (RD across-stream and 1–4 RD along-stream, and that turbines in downstream rows should be staggered to avoid wake effects of upstream turbines and to make use of the accelerated flows induced by adjacent upstream turbines.

  9. Hydrodynamic and Sediment Modelling within a Macro Tidal Estuary: Port Curtis Estuary, Australia

    Directory of Open Access Journals (Sweden)

    Ryan J. K. Dunn

    2015-07-01

    Full Text Available An understanding of sediment transport processes and resultant concentration dynamics in estuaries is of great importance to engineering design awareness and the management of these environments. Predictive modelling approaches provide an opportunity to investigate and address potential system responses to nominated events, changes, or conditions of interest, often on high temporal and spatial resolution scales. In this study, a three-dimensional hydrodynamic model and wave model were validated and applied to generate forcing conditions for input into a sediment transport model for the period 7 May 2010–30 October 2010 within a macro tidal estuary, Port Curtis estuary (Australia. The hydrodynamic model was verified against surface and near-bottom current measurements. The model accurately reproduced the variations of surface and near-bottom currents at both a mid-estuary and upper-estuary location. Sediment transport model predictions were performed under varying meteorological conditions and tidal forcing over a 180-day period and were validated against turbidity data collected at six stations within Port Curtis estuary. The sediment transport model was able to predict both the magnitudes of the turbidity levels and the modulation induced by the neap and spring tides and wind-wave variations. The model-predicted (converted turbidity levels compared favourably with the measured surface water turbidity levels at all six stations. The study results have useful practical application for Port Curtis estuary, including providing predictive capabilities to support the selection of locations for monitoring/compliance sites.

  10. Comparative Analyses of Brookhaven National Laboratory Nuclear Decay Measurements and Super-Kamiokande Solar Neutrino Measurements: Neutrinos and Neutrino-Induced Beta-Decays as Probes of the Deep Solar Interior

    Science.gov (United States)

    Sturrock, P. A.; Fischbach, E.; Scargle, J. D.

    2016-12-01

    An experiment carried out at the Brookhaven National Laboratory over a period of almost 8 years acquired 364 measurements of the beta-decay rates of a sample of {}^{32}Si and, for comparison, of a sample of {}^{36}Cl. The experimenters reported finding " small periodic annual deviations of the data points from an exponential decay … of uncertain origin". We find that power-spectrum and spectrogram analyses of these datasets show evidence not only of the annual oscillations, but also of transient oscillations with frequencies near 11 year-1 and 12.5 year-1. Similar analyses of 358 measurements of the solar neutrino flux acquired by the Super-Kamiokande neutrino observatory over a period of about 5 years yield evidence of an oscillation near 12.5 year-1 and another near 9.5 year-1. An oscillation near 12.5 year-1 is compatible with the influence of rotation of the radiative zone. We suggest that an oscillation near 9.5 year-1 may be indicative of rotation of the solar core, and that an oscillation near 11 year-1 may have its origin in a tachocline between the core and the radiative zone. Modulation of the solar neutrino flux may be attributed to an influence of the Sun's internal magnetic field by the Resonant Spin Flavor Precession (RSFP) mechanism, suggesting that neutrinos and neutrino-induced beta decays can provide information about the deep solar interior.

  11. Evolution of Tremor's Tidal Sensitivity Through the Slow Slip Cycle

    Science.gov (United States)

    Houston, H.

    2014-12-01

    Solid Earth and ocean loading tides generate stresses that modulate slow slip and tremor on deep plate boundaries. Analysis of the influence of tidal stress on 35000 tremors located in a northern Cascadia region that ruptures repeatedly in M6.5 to 6.8 slow earthquakes has yielded several new findings (Houston, 2014, subm.). Tremor sensitivity to tidal stress is low for the first day or so of activity at a spot, but increases progressively over a few days of slip at that spot, constraining the pace of weakening during ETS. After the first day or so, sensitivity varies exponentially with stress. Consideration of an isotropic pore pressure model allows an in-situ estimate of intrinsic friction on the deep subduction interface, yielding values far below lab values (i.e., mu et al, 2010). Inter-ETS tremor groups of several months duration show some sensitivity to tidal stress, although not as much as tremor during the late portions of ETS. Interestingly, I see an evolution during the 12-15 month interval between major ETSs. In particular, tidal sensitivity increases moderately toward the end of the interval as the fault is reloaded and the next large ETS is imminent. First-order features are consistent with extension of the above-mentioned model of threshold failure strength versus stress. The concept is that during the inter-ETS period, strength rebuilds as the logarithm of time (e.g., Vidale et al, 1994) since the last major ETS, while average shear or Coulomb stress on the plate interface rebuilds roughly linearly due to plate convergence. Tidal stresses become more effective in triggering tremor later in the cycle as the linearly-growing stress approaches the logarithmically-growing strength. This approach illuminates the competition between healing on the plate interface and reloading with tectonic stress, and can help constrain healing rate and conditions on the deep subduction interface.

  12. Sediment rarefaction resuspension and contaminant release under tidal curren- ts

    Institute of Scientific and Technical Information of China (English)

    程鹏达; 朱红伟; 钟宝昌; 王道增

    2014-01-01

    Based on experiment in tidal flume, this paper analyzes the sediment rarefactive phenomenon and hydraulic characteristics of sediment resuspension with different physical properties under the effect of tidal current. According to this experiment, sediment resuspension is related to the hydraulic characteristics of overlying water and its own dry density, namely the moisture content of sediment and deposition time. Generally, river sediment can be classified into the upper layer of floating sludge and lower layer of deposit sediment. Incipient velocity goes higher as the sediment layer goes thicker. Based on the experiment, incipient velocity formula of sediment can be obtained. There is a cohesive force among natural fine sediment whose resuspension is almost irrelevant to their diameters. Therefore, the critical incipient velocity is determined by the cohesive force instead of particle diameter. The lower layer of deposit sediment is generally not so easy to start up. And it will be rarified and release into the overlying water when contacting with overlying water. However, this rarefaction release velocity is gentle and slow. Under the same flow condition, annual loss amount of lower layer deposited sediment is about one fifth of upper layer of floating sediment. Flow velocity of tidal river and variation of the water level are asymmetrical, both of which vary under different tidal cycles. During long tidal cycle, flow velocity and water level change in the same phase and amplitude with tide. During the whole ebb and flow, flow direction does not change as the water level goes under the influence of acceleration and deceleration. As the tide cycle increases, the incipient velocity of sediment goes higher. This means that the long period tide cycle plays buffer effect on the resuspension of sediment, which makes the sediment not so easy both to start up and to suspend.

  13. Dynamics of Tidally Captured Planets in the Galactic Center

    Science.gov (United States)

    Trani, Alessandro A.; Mapelli, Michela; Spera, Mario; Bressan, Alessandro

    2016-11-01

    Recent observations suggest ongoing planet formation in the innermost parsec of the Galactic center. The supermassive black hole (SMBH) might strip planets or planetary embryos from their parent star, bringing them close enough to be tidally disrupted. Photoevaporation by the ultraviolet field of young stars, combined with ongoing tidal disruption, could enhance the near-infrared luminosity of such starless planets, making their detection possible even with current facilities. In this paper, we investigate the chance of planet tidal captures by means of high-accuracy N-body simulations exploiting Mikkola's algorithmic regularization. We consider both planets lying in the clockwise (CW) disk and planets initially bound to the S-stars. We show that tidally captured planets remain on orbits close to those of their parent star. Moreover, the semimajor axis of the planetary orbit can be predicted by simple analytic assumptions in the case of prograde orbits. We find that starless planets that were initially bound to CW disk stars have mild eccentricities and tend to remain in the CW disk. However, we speculate that angular momentum diffusion and scattering by other young stars in the CW disk might bring starless planets into orbits with low angular momentum. In contrast, planets initially bound to S-stars are captured by the SMBH on highly eccentric orbits, matching the orbital properties of the clouds G1 and G2. Our predictions apply not only to planets but also to low-mass stars initially bound to the S-stars and tidally captured by the SMBH.

  14. Tidal Heating and Melt Segregation and Migration within Io

    Science.gov (United States)

    Rajendar, A.; Paty, C. S.; Dufek, J.; Roberts, J. H.

    2014-12-01

    Io's volcanic activity is driven by the dissipation of energy in its interior due to tidal forces exerted by Jupiter, maintained by its orbital resonances with Europa and Ganymede. The 2011 discovery of a global partial melt layer beneath Io's surface has raised further questions about the structure of the Galilean moon and the processes that shape it. In this study we use two coupled simulations, the MFIX multiphase dynamics and the TiRADE tidal heating models, to investigate the location and extent, thermal state, melt fraction, stability, and migration of melt Io's viscous asthenosphere. We explore the feedback between melt migration and production, taking into account the rate of tidal heating and melt migration through the magma ocean layer. We begin with an assumed 1D layered internal structure based on previous investigations. This structure is input into TiRADE, which solves the equations of motion for forced oscillations in a layered spherical body using the propagator matrix method to obtain the displacements and strains due to tidal forcing. From this, we obtain the radial distribution of tidal heat generation within Io. This heating profile is then used as input for the MFIX multiphase fluid model in order to obtain the vertical flow of partially molten material, as well as the radial temperature distribution and thus the material properties and melt fractions. In the multiphase model, individual phases (melt and solid residue) separately conserve mass, momentum and enthalpy allowing us to explore melt segregation phenomena. Enthalpy closure is provided by the MELTS thermodynamics algorithm, which is called at each point in space, accounting for the partitioning between latent and sensible heat, and updating the physical properties of the melt and solid phases. This approach allows us to explore the sensitivity of melt generation to internal structure, as well as the time scales that govern melt production and eruption (i.e.: the residence and migration

  15. Periodicity in stem growth and litterfall in tidal freshwater forested wetlands: influence of salinity and drought on nitrogen recycling

    Science.gov (United States)

    Cormier, Nicole; Krauss, Ken W.; Conner, William H.

    2013-01-01

    five study years. Our data suggest that alternative processes, such as the rate of decomposition and potential for N mineralization, on tidal swamp sites undergoing salinity-induced state change may be more important for controlling N biogeochemical cycling in soils than differences among sites in N loading via litterfall.

  16. Numerical study on the impact of the 18.6-year period nodal tidal cycle on water masses in the subarctic North Pacific

    Science.gov (United States)

    Osafune, S.; Yasuda, I.

    2012-05-01

    A series of numerical experiments is performed to test the hypothesis that temporal variations in localized strong tidal mixing related to the 18.6-year period nodal tidal cycle induce water mass variations. It is suggested that enhanced mixing around the Bering Sea, as that around the Okhotsk Sea, have an impact on water masses broadly in the North Pacific including the Bering Sea and the Okhotsk Sea. Oscillatory tidal mixing with a 18.6-year period reproduces water mass variations in salinity and isopycnal potential temperature around the subarctic North Pacific that are qualitatively consistent with observed variations. When the amplitude of oscillatory vertical diffusivity is 15% of the long-term mean (and even when the amplitude is as small as 3 cm2/s, as obtained for a long-term mean of 20 cm2/s), the amplitude of the salinity variation near regions of strong mixing is smaller than but on the same order of magnitude as that observed. The induced salinity anomaly spreads broadly, over a distance of several hundreds of kilometers, by mean currents with a short lag time of less than 3 years, and is suggested to influence the model winter mixed layer over broad regions. These results support the hypothesis stated above and suggest that it is necessary to clarify spatial and temporal variations in tidal mixing to reproduce both the mean states of and temporal variations in water masses of the subarctic North Pacific.

  17. Maximum Likelihood Fitting of Tidal Streams With Application to the Sagittarius Dwarf Tidal Tails

    CERN Document Server

    Cole, Nathan; Magdon-Ismail, Malik; Desell, Travis; Dawsey, Kristopher; Hayashi, Warren; Xinyang,; Liu,; Purnell, Jonathan; Szymanski, Boleslaw; Varela, Carlos; Willett, Benjamin; Wisniewski, James

    2008-01-01

    We present a maximum likelihood method for determining the spatial properties of tidal debris and of the Galactic spheroid. With this method we characterize Sagittarius debris using stars with the colors of blue F turnoff stars in SDSS stripe 82. The debris is located at (alpha, delta, R) = (31.37 deg +/- 0.26 deg, 0.0 deg, 29.22 +/- 0.20 kpc), with a (spatial) direction given by the unit vector , in Galactocentric Cartesian coordinates, and with FWHM = 6.74 +/- 0.06 kpc. This 2.5 degee-wide stripe contains 0.892% as many F turnoff stars as the current Sagittarius dwarf galaxy. Over small spatial extent, the debris is modeled as a cylinder with a density that falls off as a Gaussian with distance from the axis, while the smooth component of the spheroid is modeled with a Hernquist profile. We assume that the absolute magnitude of F turnoff stars is distributed as a Gaussian, which is an improvement over previous methods which fixed the absolute magnitude at Mg0 = 4.2. The effectiveness and correctness of the ...

  18. Spatial and temporal variability of sediment accumulation rates on two tidal flats in Lister Dyb tidal basin, Wadden Sea, Denmark

    DEFF Research Database (Denmark)

    Madsen, A.T.; Murray, A.S.; Andersen, T.J.

    2010-01-01

    ± 100 and 5620 ± 30¿cal. BP, support the OSL chronology. The absolute chronology allowed a description of the spatial and temporal variability of intertidal sediment accumulation rates across an aggrading tidal lagoon. On the mudflat in the western and sheltered part of the lagoon the intertidal...

  19. Annual Energy Production (AEP) optimization for tidal power plants based on Evolutionary Algorithms - Swansea Bay Tidal Power Plant AEP optimization

    Science.gov (United States)

    Kontoleontos, E.; Weissenberger, S.

    2016-11-01

    In order to be able to predict the maximum Annual Energy Production (AEP) for tidal power plants, an advanced AEP optimization procedure is required for solving the optimization problem which consists of a high number of design variables and constraints. This efficient AEP optimization procedure requires an advanced optimization tool (EASY software) and an AEP calculation tool that can simulate all different operating modes of the units (bidirectional turbine, pump and sluicing mode). The EASY optimization software is a metamodel-assisted Evolutionary Algorithm (MAEA) that can be used in both single- and multi-objective optimization problems. The AEP calculation tool, developed by ANDRITZ HYDRO, in combination with EASY is used to maximize the tidal annual energy produced by optimizing the plant operation throughout the year. For the Swansea Bay Tidal Power Plant project, the AEP optimization along with the hydraulic design optimization and the model testing was used to evaluate all different hydraulic and operating concepts and define the optimal concept that led to a significant increase of the AEP value. This new concept of a triple regulated “bi-directional bulb pump turbine” for Swansea Bay Tidal Power Plant (16 units, nominal power above 320 MW) along with its AEP optimization scheme will be presented in detail in the paper. Furthermore, the use of an online AEP optimization during operation of the power plant, that will provide the optimal operating points to the control system, will be also presented.

  20. Bipolar mood cycles and lunar tidal cycles.

    Science.gov (United States)

    Wehr, T A

    2017-01-24

    In 17 patients with rapid cycling bipolar disorder, time-series analyses detected synchronies between mood cycles and three lunar cycles that modulate the amplitude of the moon's semi-diurnal gravimetric tides: the 14.8-day spring-neap cycle, the 13.7-day declination cycle and the 206-day cycle of perigee-syzygies ('supermoons'). The analyses also revealed shifts among 1:2, 1:3, 2:3 and other modes of coupling of mood cycles to the two bi-weekly lunar cycles. These shifts appear to be responses to the conflicting demands of the mood cycles' being entrained simultaneously to two different bi-weekly lunar cycles with slightly different periods. Measurements of circadian rhythms in body temperature suggest a biological mechanism through which transits of one of the moon's semi-diurnal gravimetric tides might have driven the patients' bipolar cycles, by periodically entraining the circadian pacemaker to its 24.84-h rhythm and altering the pacemaker's phase-relationship to sleep in a manner that is known to cause switches from depression to mania.Molecular Psychiatry advance online publication, 24 January 2017; doi:10.1038/mp.2016.263.