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Sample records for analysing tidally induced

  1. Analyser position for end-tidal carbon dioxide monitoring in a rebreather circuit.

    Science.gov (United States)

    Ineson, Alastair; Henderson, Kaylene; Teubner, David; Mitchell, Simon

    2010-12-01

    A diving rebreather currently nearing release incorporates an infra-red CO2 analyser at the end of the exhale hose and uses the expired gas CO2 measurement made at this position to detect hypercapnia. This configuration may allow exhaled anatomic and mouthpiece dead space gas to mix with alveolar gas in the exhale hose thus falsely lowering the CO2 measurement, especially at low tidal volumes. A test circuit was constructed using a typical rebreather mouthpiece and exhale hose connected into an anaesthetic machine breathing loop. True end-tidal PCO2 was measured in gas sampled from the mouth and compared breath-by-breath to the PCO2 measured in gas sampled at the end of the exhale hose. Two subjects each completed 60 breaths at tidal volumes of 500, 750, 1000, 1500 and 2000 ml. There was a small (≤ 0.21 kPa) mean difference between true end-tidal CO2 and end-of-hose CO2 at tidal volumes of 1000 ml or more. However, at lower tidal volumes, the mean difference increased and, at 500 ml, it was 1.04 kPa and 0.70 kPa in subjects 1 and 2 respectively. Measurement of the peak exhaled PCO2 at the end of a rebreather exhale hose may provide a reasonable estimation of the true end-tidal CO2 at large tidal volumes, but may significantly underestimate the true end-tidal CO2 at low tidal volumes.

  2. 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.

  3. Tidal double detonation: a new mechanism for the thermonuclear explosion of a white dwarf induced by a tidal disruption event

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    Tanikawa, Ataru

    2018-03-01

    We suggest tidal double detonation as a new mechanism for the thermonuclear explosion of a white dwarf (WD) induced by a tidal disruption event (TDE). Tidal detonation is also a WD explosion induced by a TDE. In this case, helium (He) and carbon-oxygen (CO) detonation waves incinerate He WDs and CO WDs, respectively. On the other hand, for tidal double detonation, He detonation is first excited in the He shell of a CO WD, which then drives CO detonation in the CO core. We name this mechanism after the double detonation scenario in the context of type Ia supernovae. In this paper, by performing numerical simulations for CO WDs of mass 0.60 M⊙ with and without a He shell, we show that tidal double detonation occurs in the shallower encounter of a CO WD with an intermediate-mass black hole (IMBH) compared to simple tidal detonation. We expect tidal double detonation will increase the possibility of the occurrence of WD TDEs, which can help us to understand IMBHs.

  4. Analysing how plants in coastal wetlands respond to varying tidal regimes throughout their life cycles.

    Science.gov (United States)

    Xie, Tian; Cui, Baoshan; Li, Shanze

    2017-10-15

    Important to conserve plant species in coastal wetlands throughout their life cycle. All life stages in these habitats are exposed to varying tidal cycles. It is necessary to investigate all life stages as to how they respond to varying tidal regimes. We examine three wetlands containing populations of an endangered halophyte species, each subjected to different tidal regimes: (1). wetlands completely closed to tidal cycles; (2). wetlands directly exposed to tidal cycles (3). wetlands exposed to a partially closed tidal regime. Our results showed that the most threatened stage varied between wetlands subjected to these varying tidal regimes. We hypothesis that populations of this species have adapted to these different tidal regimes. Such information is useful in developing management options for coastal wetlands and modifying future barriers restricting tidal flushing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Pollution induced tidal variability in water quality of Mahim Estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Zingde, M.D.; Sabnis, M.M.

    of river runoff, resulted in severe deterioration in water quality due to weak tidal flushing. The overall character of the particulate suspended matter changed considerably with increase of inorganic component from 50 per cent in the estuary to 65 and 80...

  6. Pharmacodynamic modeling of propofol-induced tidal volume depression in children.

    Science.gov (United States)

    Hahn, Jin-Oh; Khosravi, Sara; Dosani, Maryam; Dumont, Guy A; Mark Ansermino, J

    2011-08-01

    This investigation aimed to develop a pediatric pharmacodynamic model of propofol-induced tidal volume depression towards an ultimate goal of developing a dosing schedule that would preserve spontaneous breathing following a loading dose of propofol. Fifty two ASA 1 and 2 children aged 6-15 year presenting for gastrointestinal endoscopy were enrolled. Subjects were administered a loading dose of 4 mg/kg of propofol intravenously at a constant infusion rate determined by a randomization schedule. Respiratory parameters including tidal volume, respiratory rate, minute volume, and end-tidal CO(2) were recorded at 5 s intervals. Using the predicted plasma concentration, based on the Paedfusor pharmacokinetic model, propofol-induced tidal volume depression was modeled by 3 different approaches (2-stage, pooled, and mixed effects) and results were compared using prediction residual, median percentage errors, median absolute percentage errors, and root-mean-squared normalized errors. The effects of age and body weight as covariates were examined. Respiratory rate and end-tidal CO(2) did not show clear dependence on the predicted plasma concentration. The pharmacodynamic models for tidal volume derived from different modeling approaches were highly consistent. The 2-stage, pooled, and mixed effects approaches yielded k(e0) of 1.06, 1.24, and 0.72 min(-1); γ of 1.10, 0.83, and 0.93; EC50 of 3.18, 3.44, and 3.00 mcg/ml. Including age and body weight as covariates did not significantly improve the predictive performance of the models. A pediatric pharmacodynamic model of propofol-induced tidal volume depression was developed. Models derived from 3 different approaches were shown to be consistent with each other; however, the individual pharmacodynamic parameters exhibited significant inter-individual variability without strong dependence on age and body weight. This would suggest the desirability of adapting the pharmacodynamic model to each subject in real time.

  7. Are neutron stars crushed? Gravitomagnetic tidal fields as a mechanism for binary-induced collapse

    International Nuclear Information System (INIS)

    Favata, Marc

    2006-01-01

    Numerical simulations of binary neutron stars by Wilson, Mathews, and Marronetti indicated that neutron stars that are stable in isolation can be made to collapse to black holes when placed in a binary. This claim was surprising as it ran counter to the Newtonian expectation that a neutron star in a binary should be more stable, not less. After correcting an error found by Flanagan, Wilson and Mathews found that the compression of the neutron stars was significantly reduced but not eliminated. This has motivated us to ask the following general question: Under what circumstances can general-relativistic tidal interactions cause an otherwise stable neutron star to be compressed? We have found that if a nonrotating neutron star possesses a current-quadrupole moment, interactions with a gravitomagnetic tidal field can lead to a compressive force on the star. If this current quadrupole is induced by the gravitomagnetic tidal field, it is related to the tidal field by an equation-of-state-dependent constant called the gravitomagnetic Love number. This is analogous to the Newtonian Love number that relates the strength of a Newtonian tidal field to the induced mass quadrupole moment of a star. The compressive force is almost never larger than the Newtonian tidal interaction that stabilizes the neutron star against collapse. In the case in which a current quadrupole is already present in the star (perhaps as an artifact of a numerical simulation), the compressive force can exceed the stabilizing one, leading to a net increase in the central density of the star. This increase is small (< or approx. 1%) but could, in principle, cause gravitational collapse in a star that is close to its maximum mass. This paper also reviews the history of the Wilson-Mathews-Marronetti controversy and, in an appendix, extends the discussion of tidally induced changes in the central density to rotating stars

  8. TIDALLY INDUCED PULSATIONS IN KEPLER ECLIPSING BINARY KIC 3230227

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Zhao; Gies, Douglas R. [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 5060, Atlanta, GA 30302-5060 (United States); Fuller, Jim, E-mail: guo@astro.gsu.edu, E-mail: gies@chara.gsu.edu, E-mail: jfuller@caltech.edu [TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, Caltech, Pasadena, CA 91125 (United States)

    2017-01-01

    KIC 3230227 is a short period (P  ≈ 7.0 days) eclipsing binary with a very eccentric orbit ( e  = 0.6). From combined analysis of radial velocities and Kepler light curves, this system is found to be composed of two A-type stars, with masses of M {sub 1} = 1.84 ± 0.18  M {sub ⊙}, M {sub 2} = 1.73 ± 0.17  M {sub ⊙} and radii of R {sub 1} = 2.01 ± 0.09  R {sub ⊙}, R {sub 2} = 1.68 ± 0.08 R {sub ⊙} 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 10 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.

  9. A regional tidal/subtidal circulation model of the southeastern Bering Sea: development, sensitivity analyses and hindcasting

    Science.gov (United States)

    Hermann, Albert J.; Stabeno, Phyllis J.; Haidvogel, Dale B.; Musgrave, David L.

    2002-12-01

    A regional eddy-resolving primitive equation circulation model was used to simulate circulation on the southeastern Bering Sea (SEBS) shelf and basin. This model resolves the dominant observed mean currents, eddies and meanders in the region, and simultaneously includes both tidal and subtidal dynamics. Circulation, temperature, and salinity fields for years 1995 and 1997 were hindcast, using daily wind and buoyancy flux estimates, and tidal forcing derived from a global model. This paper describes the development of the regional model, a comparison of model results with available Eulerian and Lagrangian data, a comparison of results between the two hindcast years, and a sensitivity analysis. Based on these hindcasts and sensitivity analyses, we suggest the following: (1) The Bering Slope Current is a primary source of large ( ˜100 km diameter) eddies in the SEBS basin. Smaller meanders are also formed along the 100 m isobath on the southeastern shelf, and along the 200-m isobath near the shelf break. (2) There is substantial interannual variability in the statistics of eddies within the basin, driven by variability in the strength of the ANSC. (3) The mean flow on the shelf is not strongly sensitive to changes in the imposed strength of the ANSC; rather, it is strongly sensitive to the local wind forcing. (4) Vertical mixing in the SEBS is strongly affected by both tidal and subtidal dynamics. Strongest mixing in the SEBS may in fact occur between the 100- and 400-m isobaths, near the Pribilof Islands, and in Unimak Pass.

  10. Low tidal volume ventilation ameliorates left ventricular dysfunction in mechanically ventilated rats following LPS-induced lung injury.

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    Cherpanath, Thomas G V; Smeding, Lonneke; Hirsch, Alexander; Lagrand, Wim K; Schultz, Marcus J; Groeneveld, A B Johan

    2015-10-07

    High tidal volume ventilation has shown to cause ventilator-induced lung injury (VILI), possibly contributing to concomitant extrapulmonary organ dysfunction. The present study examined whether left ventricular (LV) function is dependent on tidal volume size and whether this effect is augmented during lipopolysaccharide(LPS)-induced lung injury. Twenty male Wistar rats were sedated, paralyzed and then randomized in four groups receiving mechanical ventilation with tidal volumes of 6 ml/kg or 19 ml/kg with or without intrapulmonary administration of LPS. A conductance catheter was placed in the left ventricle to generate pressure-volume loops, which were also obtained within a few seconds of vena cava occlusion to obtain relatively load-independent LV systolic and diastolic function parameters. The end-systolic elastance / effective arterial elastance (Ees/Ea) ratio was used as the primary parameter of LV systolic function with the end-diastolic elastance (Eed) as primary LV diastolic function. Ees/Ea decreased over time in rats receiving LPS (p = 0.045) and high tidal volume ventilation (p = 0.007), with a lower Ees/Ea in the rats with high tidal volume ventilation plus LPS compared to the other groups (p tidal volume ventilation without LPS (p = 0.223). A significant interaction (p tidal ventilation and LPS for Ees/Ea and Eed, and all rats receiving high tidal volume ventilation plus LPS died before the end of the experiment. Low tidal volume ventilation ameliorated LV systolic and diastolic dysfunction while preventing death following LPS-induced lung injury in mechanically ventilated rats. Our data advocates the use of low tidal volumes, not only to avoid VILI, but to avert ventilator-induced myocardial dysfunction as well.

  11. The effect of close-in giant planets' evolution on tidal-induced migration of exomoons

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    Alvarado-Montes, J. A.; Zuluaga, Jorge I.; Sucerquia, Mario

    2017-11-01

    Hypothetical exomoons around close-in giant planets may migrate inwards and/or outwards in virtue of the interplay of the star, planet and moon tidal interactions. These processes could be responsible for the disruption of lunar systems, the collision of moons with planets or could provide a mechanism for the formation of exorings. Several models have been developed to determine the fate of exomoons when subjected to the tidal effects of their host planets. None of them has taken into account the key role that planetary evolution could play in this process. In this paper, we put together numerical models of exomoon's tidal-induced orbital evolution, results of planetary evolution and interior structure models to study the final fate of exomoons around evolving close-in gas giants. We have found that planetary evolution significantly affects not only the time-scale of exomoon migration but also its final fate. Thus, if any change in planetary radius, internal mass distribution and rotation occurs in time-scales lower or comparable to orbital evolution, exomoon may only migrate outwards and prevent tidal disruption or a collision with the planet. If exomoons are discovered in the future around close-in giant planets, our results may contribute to constrain planetary evolution and internal structure models.

  12. Physical and sedimentary processes on the tidal flat of central Jiangsu Coast, China: Headland induced tidal eddies and benthic fluid mud layers

    Science.gov (United States)

    Yu, Qian; Wang, Yunwei; Shi, Benwei; Wang, Ya Ping; Gao, Shu

    2017-02-01

    An 11-tidal-cycle record time series of current, wave, suspended-sediment, and bed-level characteristics was analyzed to identify physical and sedimentary processes on the tidal flat of Jiangsu Coast, China. A tripod observation system was placed near the transition between mid and upper tidal flat south of a newly constructed harbor for hydrodynamic and sediment dynamic measurements from 27 Apr 2013 to 3 May 2013. The observations confirm the stable longshore northward (ebb direction) current s with residual velocities 59.2° anti-clockwise from the offshore direction. This phenomenon can be attributed to the effects of headland (the Harbor) induced tidal eddies based on comparable frictional length scale and the headland length scale. Benthic fluid mud layers occurred in 2 of 11 tidal cycles, with the conditions of strong waves during the flood phase. The fine sediment was resuspended by the waves and currents from the lower area, transported upward and concentrated at the observation station, resulting in the formation of a fluid mud layer with thickness of 15 cm and SSC of 8 kg/m3 at 10 cm asb. Once formed, the fluid mud layer dramatically modified the flow structure, showing a large reduction of current speed from 20 cm asb to 10 cm asb, when the gradient Richardson number was around the critical value of 0.25, inferring that sufficient turbulence from waves and currents exists to maintain fluid mud suspension. The fluid mud processes appear to occur episodically and may play an important role of sediment dynamics on the tidal flat.

  13. Low Tidal Volume Reduces Lung Inflammation Induced by Liquid Ventilation in Piglets With Severe Lung Injury.

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    Jiang, Lijun; Feng, Huizhen; Chen, Xiaofan; Liang, Kaifeng; Ni, Chengyao

    2017-05-01

    Total liquid ventilation (TLV) is an alternative treatment for severe lung injury. High tidal volume is usually required for TLV to maintain adequate CO 2 clearance. However, high tidal volume may cause alveolar barotrauma. We aim to investigate the effect of low tidal volume on pulmonary inflammation in piglets with lung injury and under TLV. After the establishment of acute lung injury model by infusing lipopolysaccharide, 12 piglets were randomly divided into two groups, TLV with high tidal volume (25 mL/kg) or with low tidal volume (6 mL/kg) for 240 min, respectively. Extracorporeal CO 2 removal was applied in low tidal volume group to improve CO 2 clearance and in high tidal volume group as sham control. Gas exchange and hemodynamic status were monitored every 30 min during TLV. At the end of the study, pulmonary mRNA expression and plasmatic concentration of interleukin-6 (IL-6) and interleukin-8 (IL-8) were measured by collecting lung tissue and blood samples from piglets. Arterial blood pressure, PaO 2 , and PaCO 2 showed no remarkable difference between groups during the observation period. Compared with high tidal volume strategy, low tidal volume resulted in 76% reduction of minute volume and over 80% reduction in peak inspiratory pressure during TLV. In addition, low tidal volume significantly diminished pulmonary mRNA expression and plasmatic level of IL-6 and IL-8. We conclude that during TLV, low tidal volume reduces lung inflammation in piglets with acute lung injury without compromising gas exchange. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  14. 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.

    Biolog plates were used to study the changes in the metabolic capabilities of bacterioplankton over a complete tidal cycle in a tropical ecosystem (Cochin Estuary, Kerala, India) along southwest coast of India. The pattern of utilization of carbon...

  15. 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

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

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    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.

  17. Tidal-Induced Internal Ocean Waves as an Explanation for Enceladus' Tiger Stripe Pattern and Hotspot Activity

    Science.gov (United States)

    Vermeersen, B. L. A.; Maas, L. R.; van Oers, S.; Rabitti, A.; Jara-Orue, H.

    2014-12-01

    One of the most peculiar features on Saturn moon Enceladus is its so-called tiger stripe pattern at the geologically active South Polar Terrain (SPT), as first observed in detail by the Cassini spacecraft early 2005. It is generally assumed that the four almost parallel surface lines that constitute this pattern are faults in the icy surface overlying a confined salty water reservoir. Indeed, later Cassini observations have shown that salty water jets originate from the tiger stripes [e.g., Hansen et al., Science, 311, 1422-1425, 2006; Postberg et al., Nature, 474, 620-622, 2011]. More recently, Porco et al. [Astron. J., 148:45, Sep. 2014] and Nimmo et al. [Astron. J., 148:46, Sep. 2014] have reported strong evidence that the geysers are not caused by frictional heating at the surface, but that geysers must originate deeper in Enceladus' interior. Tidal flexing models, like those of Hurford et al., Nature, 447, 292-294, 2007, give a good match for the brightness variations Cassini observes, but they seem to fail to reproduce the exact timing of plume brightening. Although jet activity is thus strongly connected to tidal forcing, another mechanism must be involved as well. Last year, we formulated the original idea [Vermeersen et al., AGU Fall Meeting 2013, abstract #P53B-1848] that the tiger stripe pattern is formed and maintained by induced, tidally and rotationally driven, wave-attractor motions in the ocean underneath the icy surface of the tiger-stripe region. Such wave-attractor motions are observed in water tank experiments in laboratories on Earth and in numerical experiments [Maas et al., Nature, 338, 557-561, 1997; Drijfhout and Maas, J. Phys. Oceanogr., 37, 2740-2763, 2007; Hazewinkel et al., Phys. Fluids, 22, 107102, 2010]. The latest observations by Porco et al. and Nimmo et al. seem to be in agreement with this tidal-induced wave attractor phenomenon, both with respect to tiger stripe pattern and with respect to timing of hotspot activity. However, in

  18. Tidal power

    International Nuclear Information System (INIS)

    Baker, A.C.

    1991-01-01

    This book describes how large tides develop in particular places and how the energy could be extracted by building suitable barrages. The principal features of a barrage and possible methods of operation are described in detail. Although a tidal power barrage would be non-polluting, the resulting changes in the tidal regime would have important environmental effects. These are discussed together with the economics of tidal power. Methods of assessing the likely cost of electricity from any site are set out and applied to possible sites around the world. (author)

  19. Tidal radiation

    International Nuclear Information System (INIS)

    Mashhoon, B.

    1977-01-01

    The general theory of tides is developed within the framework of Einstein's theory of gravitation. It is based on the concept of Fermi frame and the associated notion of tidal frame along an open curve in spacetime. Following the previous work of the author an approximate scheme for the evaluation of tidal gravitational radiation is presented which is valid for weak gravitational fields. The emission of gravitational radiation from a body in the field of a black hole is discussed, and for some cases of astrophysical interest estimates are given for the contributions of radiation due to center-of-mass motion, purely tidal deformation, and the interference between the center of mass and tidal motions

  20. Tidal Energy.

    Science.gov (United States)

    Impact of Science on Society, 1987

    1987-01-01

    States that tidal power projects are feasible in a relatively limited number of locations around the world. Claims that together they could theoretically produce the energy equivalent to more than one million barrels of oil per year. (TW)

  1. Role of bronchodilation and pattern of breathing in increasing tidal expiratory flow with progressive induced hypercapnia in chronic obstructive pulmonary disease.

    Science.gov (United States)

    Finucane, Kevin E; Singh, Bhajan

    2018-01-01

    Hypercapnia (HC) in vitro relaxes airway smooth muscle; in vivo, it increases respiratory effort, tidal expiratory flows (V̇ exp ), and, by decreasing inspiratory duration (Ti), increases elastic recoil pressure (Pel) via lung viscoelasticity; however, its effect on airway resistance is uncertain. We examined the contributions of bronchodilation, Ti, and expiratory effort to increasing V̇ exp with progressive HC in 10 subjects with chronic obstructive pulmonary disease (COPD): mean forced expiratory volume in 1 s (FEV 1 ) 53% predicted. Lung volumes (Vl), V̇ exp , esophageal pressure (Pes), Ti, and end-tidal Pco 2 ([Formula: see text]) were measured during six tidal breaths followed by an inspiratory capacity (IC), breathing air, and at three levels of HC. V̇ exp and V̇ with submaximal forced vital capacities breathing air (V̇ sFVC ) were compared. Pulmonary resistance ( Rl) was measured from the Pes-V̇ relationship. V̇ exp and Pes at end-expiratory lung volume (EELV) + 0.3 tidal volume [V̇ (0.3Vt) and Pes (0.3Vt) , respectively], Ti, and Rl correlated with [Formula: see text] ( P tidal expiratory flows by inducing bronchodilation and via an increased rate of inspiration and lung viscoelasticity, a probable increase in lung elastic recoil pressure, both changes increasing expiratory flows, promoting lung emptying and a stable end-expiratory volume. Bronchodilation with HC occurred despite optimal standard bronchodilator therapy, suggesting that in COPD further bronchodilation is possible.

  2. Impact of Different Tidal Volume Levels at Low Mechanical Power on Ventilator-Induced Lung Injury in Rats

    Directory of Open Access Journals (Sweden)

    Lillian Moraes

    2018-04-01

    Full Text Available Tidal volume (VT has been considered the main determinant of ventilator-induced lung injury (VILI. Recently, experimental studies have suggested that mechanical power transferred from the ventilator to the lungs is the promoter of VILI. We hypothesized that, as long as mechanical power is kept below a safe threshold, high VT should not be injurious. The present study aimed to investigate the impact of different VT levels and respiratory rates (RR on lung function, diffuse alveolar damage (DAD, alveolar ultrastructure, and expression of genes related to inflammation [interleukin (IL-6], alveolar stretch (amphiregulin, epithelial [club cell secretory protein (CC16] and endothelial [intercellular adhesion molecule (ICAM-1] cell injury, and extracellular matrix damage [syndecan-1, decorin, and metalloproteinase (MMP-9] in experimental acute respiratory distress syndrome (ARDS under low-power mechanical ventilation. Twenty-eight Wistar rats received Escherichia coli lipopolysaccharide intratracheally. After 24 h, 21 animals were randomly assigned to ventilation (2 h with low mechanical power at three different VT levels (n = 7/group: (1 VT = 6 mL/kg and RR adjusted to normocapnia; (2 VT = 13 mL/kg; and 3 VT = 22 mL/kg. In the second and third groups, RR was adjusted to yield low mechanical power comparable to that of the first group. Mechanical power was calculated as [(ΔP,L2/Est,L/2]× RR (ΔP,L = transpulmonary driving pressure, Est,L = static lung elastance. Seven rats were not mechanically ventilated (NV and were used for molecular biology analysis. Mechanical power was comparable among groups, while VT gradually increased. ΔP,L and mechanical energy were higher in VT = 22 mL/kg than VT = 6 mL/kg and VT = 13 mL/kg (p < 0.001 for both. Accordingly, DAD score increased in VT = 22 mL/kg compared to VT = 6 mL/kg and VT = 13 mL/kg [23(18.5–24.75 vs. 16(12–17.75 and 16(13.25–18, p < 0.05, respectively]. VT = 22 mL/kg was associated with higher

  3. Increased tidal volume variability in children is a better marker of opioid-induced respiratory depression than decreased respiratory rate.

    Science.gov (United States)

    Barbour, Sean J; Vandebeek, Christine A; Ansermino, J Mark

    2004-06-01

    During opioid administration, decreasing respiratory rate is typically used as a predictor of respiratory depression. Prior to opioid-induced apnea, progressively irregular breathing patterns have been noticed. We hypothesize that opioid administration to children will increase tidal volume variability (TV(var)) and that this will be a better predictor of respiratory depression than a decrease in respiratory rate. We recruited 32 children aged 2-8 years scheduled to undergo surgery. During spontaneous ventilation, flow rates and respiratory rates were continuously recorded, while remifentanil was infused at stepwise increasing doses each lasting 10 min. The infusion was continued until the patient showed signs of respiratory depression. Flow data from each dose was used to calculate tidal volumes, from which TV(var) was calculated. The respiratory rate and TV(var) during the last (D(last)), second to last (D-2), and third to last (D-3), administered doses were compared to those during baseline (fourth to last dose). We chose a threshold of TV(var) increase and compared it to a decrease in respiratory rate below 10 breaths per min as predictors of respiratory depression. Compared to baseline, the TV(var) increased by 336% and 668% during D(-2) and D(last), respectively, whereas respiratory rate decreased by 14.3%, 31.7%, and 55.5% during D(-3), D(-2), and D(last), respectively. A threshold increase in TV(var) of 150% over baseline correctly predicted respiratory depression in 41% of patients, compared to a drop in respiratory rate correctly predicting 22% of patients. TV(var) increases as children approach opioid-induced respiratory depression. This is a more useful predictor of respiratory depression than a fall in respiratory rate because the TV(var) increase is 10 times the drop in respiratory rate. A TV(var) increase also correctly predicts respiratory depression twice as often as decreased respiratory rate and is independent of age-related alterations in

  4. Coupled in situ Ammonium and Nitrate analyses of a tidally dominated estuary: New developments from the Elkhorn Slough Land/Ocean Biogeochemical Observatory network

    Science.gov (United States)

    Gibson, P. J.; Plant, J.; Johnson, K. S.

    2012-12-01

    For nearly nine years the Elkhorn Slough Land/Ocean Biogeochemical Observatory (LOBO) network of moorings has been delivering freely available hourly data to the web in near real time. Each mooring hosts a suite of instruments including an ISUS nitrate sensor. In addition to providing valuable information on ecosystem scale processes, the moorings serve as ideal test platforms for novel in situ chemical sensors & analyzers developed by the Monterey Bay Aquarium Research Institute. The recent addition of a newly developed in situ NH4+ analyzer, the DigiScan-II, has provided additional insights into N cycling mechanisms within the slough. The analysis method estimates NH4+ concentration via base conversion to NH3 gas and diffusion across a membrane into an acid carrier stream with subsequent conductivity detection. Although this new NH4+ analyzer is reagent based, it was developed to be relatively cheap, robust, and configurable for a range of deployment options and requires minimal, infrequent maintenance that is ultimately governed by battery life. The fundamental DigiScan-II platform can also be used for other analyses of interest, such as PO4 or CT (total inorganic carbon), by swapping the necessary reagents and components and by making minor code modifications. For deployment in Elkhorn Slough, the NH4+ DigiScan-II was configured for mid-scale concentration detection with a linear calibration range of 30.0 μM NH4+. The flux of different forms of bioavailable DIN through the system is driven by runoff inputs, tidal exchange, and biological processing. Large inputs of NO3- are sourced from the agriculturally influenced Old Salinas River (OSR), which enters the Slough near the estuary mouth and confluence with Monterey Bay. Rising ocean tides force this eutrophied water mass up into the slough where it is accessed by various biological communities during the course of the tidal period. Mass balance estimates suggest there is an imbalance between the amount of NO3

  5. Tides and tidal currents

    NARCIS (Netherlands)

    Roos, A.

    1997-01-01

    Basic phenomena, origin and generation of tides, analysis and prediction of tides, basic equation and types of long waves in one dimension, tidal propagation in one dimension, tidal propagation in two directions, analytical tidal computation, numerical tidal computation.

  6. Tidal Venuses: triggering a climate catastrophe via tidal heating.

    Science.gov (United States)

    Barnes, Rory; Mullins, Kristina; Goldblatt, Colin; Meadows, Victoria S; Kasting, James F; Heller, René

    2013-03-01

    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 (i.e., with negligible tidal heating) 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 simulated the evolution of hypothetical planetary systems in a quasi-continuous parameter distribution and found that we could constrain the history of the system by statistical arguments. Planets orbiting stars with massesplanet orbiting a 0.3 MSun star at 0.12 AU. We found that it probably did not lose its water via tidal heating, as orbital stability is unlikely for the high eccentricities required for the tidal greenhouse. As the inner edge of the HZ is defined by the onset of a runaway or moist greenhouse powered by radiation, our results represent a fundamental revision to the HZ for noncircular orbits. In the appendices we review (a) the moist and runaway greenhouses, (b) hydrogen escape, (c) stellar mass-radius and mass-luminosity relations, (d) terrestrial planet mass-radius relations, and (e) linear tidal theories.

  7. Modelling tidal current-induced bed shear stress and palaeocirculation in an epicontinental seaway: the Bohemian Cretaceous Basin, Central Europe

    Czech Academy of Sciences Publication Activity Database

    Mitchell, A. J.; Uličný, David; Hampson, G. J.; Allison, P. A.; Gorman, G. J.; Piggott, M. D.; Wells, M. R.; Pain, C. C.

    2010-01-01

    Roč. 57, č. 2 (2010), s. 359-388 ISSN 0037-0746 R&D Projects: GA AV ČR(CZ) IAA300120609 Institutional research plan: CEZ:AV0Z30120515 Keywords : bed shear stress * Bohemian Cretaceous Basin * epicontinental sea * tidal circulation * Turonian Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.229, year: 2010

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

    Science.gov (United States)

    Mullins, Kristina; Goldblatt, Colin; Meadows, Victoria S.; Kasting, James F.; Heller, René

    2013-01-01

    Abstract 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 (i.e., with negligible tidal heating) 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 simulated the evolution of hypothetical planetary systems in a quasi-continuous parameter distribution and found that we could constrain the history of the system by statistical arguments. Planets orbiting stars with massestidal heating. We have applied these concepts to Gl 667C c, a ∼4.5 MEarth planet orbiting a 0.3 MSun star at 0.12 AU. We found that it probably did not lose its water via tidal heating, as orbital stability is unlikely for the high eccentricities required for the tidal greenhouse. As the inner edge of the HZ is defined by the onset of a runaway or moist greenhouse powered by radiation, our results represent a fundamental revision to the HZ for noncircular orbits. In the appendices we review (a) the moist and runaway greenhouses, (b) hydrogen escape, (c) stellar mass-radius and mass-luminosity relations, (d) terrestrial planet mass-radius relations, and (e) linear tidal theories. Key Words: Extrasolar terrestrial planets—Habitability—Habitable zone

  9. Tidal acceleration of black holes and superradiance

    International Nuclear Information System (INIS)

    Cardoso, Vitor; Pani, Paolo

    2013-01-01

    Tidal effects have long ago locked the Moon in a synchronous rotation with the Earth and progressively increase the Earth–Moon distance. This ‘tidal acceleration’ hinges on dissipation. Binaries containing black holes may also be tidally accelerated, dissipation being caused by the event horizon—a flexible, viscous one-way membrane. In fact, this process is known for many years under a different guise: superradiance. Here, we provide compelling evidence for a strong connection between tidal acceleration and superradiant scattering around spinning black holes. In general relativity, tidal acceleration is obscured by the gravitational-wave emission. However, when coupling to light scalar degrees of freedom is allowed, an induced dipole moment produces a ‘polarization acceleration’, which might be orders of magnitude stronger than tidal quadrupolar effects. Consequences for optical and gravitational-wave observations are intriguing and it is not impossible that imprints of such a mechanism have already been observed. (paper)

  10. Tidal locking of habitable exoplanets

    Science.gov (United States)

    Barnes, Rory

    2017-12-01

    Potentially habitable planets can orbit close enough to their host star that the differential gravity across their diameters can produce an elongated shape. Frictional forces inside the planet prevent the bulges from aligning perfectly with the host star and result in torques that alter the planet's rotational angular momentum. Eventually the tidal torques fix the rotation rate at a specific frequency, a process called tidal locking. Tidally locked planets on circular orbits will rotate synchronously, but those on eccentric orbits will either librate or rotate super-synchronously. Although these features of tidal theory are well known, a systematic survey of the rotational evolution of potentially habitable exoplanets using classic equilibrium tide theories has not been undertaken. I calculate how habitable planets evolve under two commonly used models and find, for example, that one model predicts that the Earth's rotation rate would have synchronized after 4.5 Gyr if its initial rotation period was 3 days, it had no satellites, and it always maintained the modern Earth's tidal properties. Lower mass stellar hosts will induce stronger tidal effects on potentially habitable planets, and tidal locking is possible for most planets in the habitable zones of GKM dwarf stars. For fast-rotating planets, both models predict eccentricity growth and that circularization can only occur once the rotational frequency is similar to the orbital frequency. The orbits of potentially habitable planets of very late M dwarfs ([InlineEquation not available: see fulltext.]) are very likely to be circularized within 1 Gyr, and hence, those planets will be synchronous rotators. Proxima b is almost assuredly tidally locked, but its orbit may not have circularized yet, so the planet could be rotating super-synchronously today. The evolution of the isolated and potentially habitable Kepler planet candidates is computed and about half could be tidally locked. Finally, projected TESS planets

  11. How Tidal Forces Cause Ocean Tides in the Equilibrium Theory

    Science.gov (United States)

    Ng, Chiu-king

    2015-01-01

    We analyse why it is erroneous to think that a tidal bulge is formed by pulling the water surface directly up by a local vertical tidal force. In fact, ocean tides are caused by the global effect of the horizontal components of the tidal forces.

  12. Potpourri of proton induced x-ray emission analyses

    International Nuclear Information System (INIS)

    Mangelson, N.F.; Nielson, K.K.; Eatough, D.J.; Hansen, L.D.

    1974-01-01

    A proton-induced x-ray emission analysis (PIXE) system using 2-MeV protons was developed. Measurements are being made in connection with several research projects. A study is being conducted to provide ecological baseline information in the region of the Navajo and the proposed Kaiparowits coal-fired electric generating stations. Trace-element measurements in this study are reported on air-particulate samples, small rodent tissues, soils, and plants. In another study air particulates collected near a source of SO 2 are extracted from the collection filter with an HCl solution and sulfate and sulfite ions are determined by calorimetric methods. The extraction solution is also analyzed by PIXE to determine the elemental composition. The latter information is necessary for an understanding of possible interferences with the calorimetric method and also indicates the heavy metals emitted by the source. Studies on human autopsy tissues, archeological artifacts, and in regular graduate and undergraduate laboratory classes are mentioned briefly

  13. 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.

  14. Dissipation of Tidal Energy

    Science.gov (United States)

    2002-01-01

    accounting for tidally induced ocean mixing may have important implications for long-term climate modeling', Egbert said. In the past, most geophysical theories held that the only significant tidal energy sink was bottom friction in shallow seas. Egbert and Ray find that this sink is indeed dominant, but it is not the whole story. There had always been suggestive evidence that tidal energy is also dissipated in the open ocean to create internal waves, but published estimates of this effect varied widely and had met with no general consensus before TOPEX/Poseidon. TOPEX/Poseidon mission, a joint U.S.-French mission, is managed by the Jet Propulsion Laboratory for NASA's Office of Earth Science, Washington, DC. The satellite was launched in August 1992, and it continues to produce sea level measurements of the highest quality. For supporting images: http://svs.gsfc.nasa.gov/search/Instrumentsdatasets/TOPEX-POSEIDON.html Image by Richard Ray, NASA GSFC

  15. The influence of waves on the tidal kinetic energy resource at a tidal stream energy site

    International Nuclear Information System (INIS)

    Guillou, Nicolas; Chapalain, Georges; Neill, Simon P.

    2016-01-01

    Highlights: • We model the influence of waves on tidal kinetic energy in the Fromveur Strait. • Numerical results are compared with field data of waves and currents. • The introduction of waves improve predictions of tidal stream power during storm. • Mean spring tidal stream potential is reduced by 12% during extreme wave conditions. • Potential is reduced by 7.8% with waves forces and 5.3% with enhanced friction. - Abstract: Successful deployment of tidal energy converters relies on access to accurate and high resolution numerical assessments of available tidal stream power. However, since suitable tidal stream sites are located in relatively shallow waters of the continental shelf where tidal currents are enhanced, tidal energy converters may experience effects of wind-generated surface-gravity waves. Waves may thus influence tidal currents, and associated kinetic energy, through two non-linear processes: the interaction of wave and current bottom boundary layers, and the generation of wave-induced currents. Here, we develop a three-dimensional tidal circulation model coupled with a phase-averaged wave model to quantify the impact of the waves on the tidal kinetic energy resource of the Fromveur Strait (western Brittany) - a region that has been identified with strong potential for tidal array development. Numerical results are compared with in situ observations of wave parameters (significant wave height, peak period and mean wave direction) and current amplitude and direction 10 m above the seabed (the assumed technology hub height for this region). The introduction of waves is found to improve predictions of tidal stream power at 10 m above the seabed at the measurement site in the Strait, reducing kinetic energy by up to 9% during storm conditions. Synoptic effects of wave radiation stresses and enhanced bottom friction are more specifically identified at the scale of the Strait. Waves contribute to a slight increase in the spatial gradient of

  16. Tidal energy update 2009

    Energy Technology Data Exchange (ETDEWEB)

    O Rourke, Fergal; Boyle, Fergal; Reynolds, Anthony [Department of Mechanical Engineering, Dublin Institute of Technology, Bolton Street, Dublin 1 (Ireland)

    2010-02-15

    Tidal energy has the potential to play a valuable part in a sustainable energy future. It is an extremely predictable energy source, depending only on the gravitational pull of the moon and the sun and the centrifugal forces created by the rotation of the earth-moon system. Tidal energy has been exploited on a significant scale since the construction of the La Rance tidal barrage in France in 1967. A tidal barrage utilises the potential energy of the tide and has proven to be very successful, despite opposition from environmental groups. Kinetic energy can also be harnessed from tidal currents to generate electricity and involves the use of a tidal current turbine. This is the more desired method of capturing the energy in the tides. However, tidal current turbine technology is currently not economically viable on a large scale, as it is still in an early stage of development. This paper provides an up-to-date review of the status of tidal energy technology and identifies some of the key barriers challenging the development of tidal energy. The future development of tidal current devices and tidal barrage systems is discussed as well as examining the importance of a supportive policy to assist development. (author)

  17. Endotracheal tube cuff pressure assessment maneuver induces drop of expired tidal volume in the postoperative of coronary artery bypass grafting

    Directory of Open Access Journals (Sweden)

    Bolzan Douglas W

    2012-06-01

    Full Text Available Abstract Background Previous investigations reported that the cuff pressure (CP can decrease secondary to the CP evaluation itself. However is not established in literature if this loss of CP is able to generate alterations on expired tidal volume (ETV. Therefore, the aim of this study was to evaluate the potential consequences of the endotracheal CP assessment maneuver on CP levels and ETV in the early postoperative of coronary artery bypass grafting (CABG. Methods A total of 488 patients were analyzed. After the operation, the lungs were ventilated in pressure-assist-control mode and the same ventilatory settings were adjusted for all patients. After intensive care unit arrival, the cuff was fully deflated and then progressively inflated by air injection, to promote a minimal volume to occlude the trachea. To assist the cuff inflation and the air leakage identification, the graphical monitoring of the volume-time curve was adopted. After 20 minutes a first cuff pressure evaluation was performed (P1 and a second measurement (P2 was taken after 20 minutes with an analog manometer. ETV was obtained always pre and post P1 measurement. Results The CP assessment maneuver promoted a significant drop of P2 in relation to P1 when the manometer was attached to the pilot balloon (p  Conclusion The CP assessment maneuver promoted a significant decrease in CP values and occurrence of air leakage with reduction of ETV in the early postoperative of CABG.

  18. Relevance of tidal heating on large TNOs

    Science.gov (United States)

    Saxena, Prabal; Renaud, Joe P.; Henning, Wade G.; Jutzi, Martin; Hurford, Terry

    2018-03-01

    We examine the relevance of tidal heating for large Trans-Neptunian Objects, with a focus on its potential to melt and maintain layers of subsurface liquid water. Depending on their past orbital evolution, tidal heating may be an important part of the heat budget for a number of discovered and hypothetical TNO systems and may enable formation of, and increased access to, subsurface liquid water. Tidal heating induced by the process of despinning is found to be particularly able to compete with heating due to radionuclide decay in a number of different scenarios. In cases where radiogenic heating alone may establish subsurface conditions for liquid water, we focus on the extent by which tidal activity lifts the depth of such conditions closer to the surface. While it is common for strong tidal heating and long lived tides to be mutually exclusive, we find this is not always the case, and highlight when these two traits occur together. We find cases where TNO systems experience tidal heating that is a significant proportion of, or greater than radiogenic heating for periods ranging from100‧s of millions to a billion years. For subsurface oceans that contain a small antifreeze component, tidal heating due to very high initial spin states may enable liquid water to be preserved right up to the present day. Of particular interest is the Eris-Dysnomia system, which in those cases may exhibit extant cryovolcanism.

  19. Tidal Energy Update 2009

    OpenAIRE

    O'Rourke, Fergal; Boyle, Fergal; Reynolds, Anthony

    2010-01-01

    Tidal energy has the potential to play a valuable part in a sustainable energy future. It is an extremely predictable energy source, depending only on the gravitational pull of the moon and the sun and the centrifugal forces created by the rotation of the earth-moon system. Tidal energy has been exploited on a significant scale since the construction of the La Rance tidal barrage in France in 1967. A tidal barrage utilises the potential energy of the tide and has proven to be very successful,...

  20. 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

  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). Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Tidally influenced alongshore circulation at an inlet-adjacent shoreline

    Science.gov (United States)

    Hansen, Jeff E.; Elias, Edwin P.L.; List, Jeffrey H.; Erikson, Li H.; Barnard, Patrick L.

    2013-01-01

    The contribution of tidal forcing to alongshore circulation inside the surfzone is investigated at a 7 km long sandy beach adjacent to a large tidal inlet. Ocean Beach in San Francisco, CA (USA) is onshore of a ∼150 km2 ebb-tidal delta and directly south of the Golden Gate, the sole entrance to San Francisco Bay. Using a coupled flow-wave numerical model, we find that the tides modulate, and in some cases can reverse the direction of, surfzone alongshore flows through two separate mechanisms. First, tidal flow through the inlet results in a barotropic tidal pressure gradient that, when integrated across the surfzone, represents an important contribution to the surfzone alongshore force balance. Even during energetic wave conditions, the tidal pressure gradient can account for more than 30% of the total alongshore pressure gradient (wave and tidal components) and up to 55% during small waves. The wave driven component of the alongshore pressure gradient results from alongshore wave height and corresponding setup gradients induced by refraction over the ebb-tidal delta. Second, wave refraction patterns over the inner shelf are tidally modulated as a result of both tidal water depth changes and strong tidal flows (∼1 m/s), with the effect from currents being larger. These tidally induced changes in wave refraction result in corresponding variability of the alongshore radiation stress and pressure gradients within the surfzone. Our results indicate that tidal contributions to the surfzone force balance can be significant and important in determining the direction and magnitude of alongshore flow.

  3. Tidal power in Norway

    International Nuclear Information System (INIS)

    2003-01-01

    The world's first tidal power station is scheduled for stat-up in the spring of 2003. It is located in Kvalsundet, off Hammerfest, Norway. This is a pilot installation of a 300 kW tidal turbine at a depth of 50 metres. When fully developed in 2007, the tidal power plant will deliver 32 GWh per year. Hammerfest Stroem has patented the energy and the company hopes to be able to install similar power stations both in Norway and abroad. The potential worldwide is claimed to be more than 450 TWh per year

  4. Tidal viscosity of Enceladus

    Science.gov (United States)

    Efroimsky, Michael

    2018-01-01

    In the preceding paper (Efroimsky, 2017), we derived an expression for the tidal dissipation rate in a homogeneous near-spherical Maxwell body librating in longitude. Now, by equating this expression to the outgoing energy flux due to the vapour plumes, we estimate the mean tidal viscosity of Enceladus, under the assumption that the Enceladean mantle behaviour is Maxwell. This method yields a value of 0.24 × 1014 Pa s for the mean tidal viscosity, which is very close to the viscosity of ice near the melting point.

  5. The effects of tidal range on saltmarsh morphology

    Science.gov (United States)

    Goodwin, Guillaume; Mudd, Simon

    2017-04-01

    Saltmarshes are highly productive coastal ecosystems that act simultaneously as flood barriers, carbon storage, pollutant filters and nurseries. As halophytic plants trap suspended sediment and decay in the settled strata, innervated platforms emerge from the neighbouring tidal flats, forming sub-vertical scarps on their eroding borders and sub-horizontal pioneer zones in areas of seasonal expansion. These evolutions are subject to two contrasting influences: stochastically generated waves erode scarps and scour tidal flats, whereas tidally-generated currents transport sediment to and from the marsh through the channel network. Hence, the relative power of waves and tidal currents strongly influences saltmarsh evolution, and regional variations in tidal range yield marshes of differing morphologies. We analyse several sheltered saltmarshes to determine how their morphology reflects variations in tidal forcing. Using tidal, topographic and spectral data, we implement an algorithm based on the open-source software LSDTopoTools to automatically identify features such as marsh platforms, tidal flats, erosion scarps, pioneer zones and tidal channels on local Digital Elevation Models. Normalised geometric properties are then computed and compared throughout the spectrum of tidal range, highlighting a notable effect on channel networks, platform geometry and wave exposure. We observe that micro-tidal marshes typically display jagged outlines and multiple islands along with wide, shallow channels. As tidal range increases, we note the progressive disappearance of marsh islands and linearization of scarps, both indicative of higher hydrodynamic stress, along with a structuration of channel networks and the increase of levee volume, suggesting higher sediment input on the platform. Future research will lead to observing and modelling the evolution of saltmarshes under various tidal forcing in order to assess their resilience to environmental change.

  6. Tidal alignment of galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Blazek, Jonathan; Vlah, Zvonimir; Seljak, Uroš

    2015-08-01

    We develop an analytic model for galaxy intrinsic alignments (IA) based on the theory of tidal alignment. We calculate all relevant nonlinear corrections at one-loop order, including effects from nonlinear density evolution, galaxy biasing, and source density weighting. Contributions from density weighting are found to be particularly important and lead to bias dependence of the IA amplitude, even on large scales. This effect may be responsible for much of the luminosity dependence in IA observations. The increase in IA amplitude for more highly biased galaxies reflects their locations in regions with large tidal fields. We also consider the impact of smoothing the tidal field on halo scales. We compare the performance of this consistent nonlinear model in describing the observed alignment of luminous red galaxies with the linear model as well as the frequently used "nonlinear alignment model," finding a significant improvement on small and intermediate scales. We also show that the cross-correlation between density and IA (the "GI" term) can be effectively separated into source alignment and source clustering, and we accurately model the observed alignment down to the one-halo regime using the tidal field from the fully nonlinear halo-matter cross correlation. Inside the one-halo regime, the average alignment of galaxies with density tracers no longer follows the tidal alignment prediction, likely reflecting nonlinear processes that must be considered when modeling IA on these scales. Finally, we discuss tidal alignment in the context of cosmic shear measurements.

  7. Numerical Analyses of Earthquake Induced Liquefaction and Deformation Behaviour of an Upstream Tailings Dam

    Directory of Open Access Journals (Sweden)

    Muhammad Auchar Zardari

    2017-01-01

    Full Text Available Much of the seismic activity of northern Sweden consists of micro-earthquakes occurring near postglacial faults. However, larger magnitude earthquakes do occur in Sweden, and earthquake statistics indicate that a magnitude 5 event is likely to occur once every century. This paper presents dynamic analyses of the effects of larger earthquakes on an upstream tailings dam at the Aitik copper mine in northern Sweden. The analyses were performed to evaluate the potential for liquefaction and to assess stability of the dam under two specific earthquakes: a commonly occurring magnitude 3.6 event and a more extreme earthquake of magnitude 5.8. The dynamic analyses were carried out with the finite element program PLAXIS using a recently implemented constitutive model called UBCSAND. The results indicate that the magnitude 5.8 earthquake would likely induce liquefaction in a limited zone located below the ground surface near the embankment dikes. It is interpreted that stability of the dam may not be affected due to the limited extent of the liquefied zone. Both types of earthquakes are predicted to induce tolerable magnitudes of displacements. The results of the postseismic slope stability analysis, performed for a state after a seismic event, suggest that the dam is stable during both the earthquakes.

  8. Mining CANDELS for Tidal Features to Constrain Major Merging During Cosmic Noon

    Science.gov (United States)

    McIntosh, Daniel H.; Mantha, Kameswara; Ciaschi, Cody; Evan, Rubyet A.; Fries, Logan B.; Landry, Luther; Thompson, Scott E.; Snyder, Gregory; Guo, Yicheng; Ceverino, Daniel; Häuβler, Boris; Primack, Joel; Simons, Raymond C.; Zheng, Xianzhong; Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) Team

    2018-01-01

    The role of major merging in the rapid buildup and development of massive galaxies at z>1 remains an open question. New theories and observations suggest that non-merging processes like violent disk instabilities may be more vital than previously thought at assembling bulges, producing clumps, and inducing morphological disturbances that may be misinterpreted as the product of major merging. We will present initial results on a systematic search for hallmark tidal indicators of major merging in a complete sample of nearly 6000 massive z>1 galaxies from CANDELS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey), the premiere HST/WFC3 Treasury program. We have visually inspected published GALFIT F160W residual (image-model) maps and produced a comprehensive new catalog of Sersic residual characteristics based on a variety of natural features and poor-fit artifacts. Using this catalog, we find the frequency of galaxies with tidal signatures is very small in CANDELS data. Accounting for the brief time scale associated with faint transient tidal features, our preliminary finding indicates that merger fractions derived from the CANDELS morphological classification efforts are substantially overestimated. We are using the database of residual classifications as a baseline to (1) produce improved multi-component residual maps using GALFIT_M, (2) automatically extract and quantify plausible tidal indicators and substructures (clumps vs. multiple nuclei), (3) develop a new deep-learning classification pipeline to robustly identify merger indicators in imaging data, and (4) inform the systematic analyses of synthetic mock (CANDELized) images from zoom-in hydrodynamic simulations to thoroughly quantify the impacts of cosmological dimming, and calibrate the observability timescale of tidal feature detections. Our study will ultimately yield novel constraints on merger rates at z>1 and a definitive census of massive high-noon galaxies with tidal and double

  9. Restoration of estuarine tidal mudflat sediments after hypoxia

    DEFF Research Database (Denmark)

    Van Colen, Carl; Montserrat, F; Middelburg, JJ

    Ecosystem function recovery and benthic community recovery was investigated after experimentally induced depleted oxygen bottom water concentrations in a tidal mudflat (Paulinapolder, Westerschelde estuary). Macrofauna recovery developed through different succession stages and was structured...

  10. Carbohydrate secretion by phototrophic communities in tidal sediments

    NARCIS (Netherlands)

    de Winder, B.; Staats, N.; Stal, L.J.; Paterson, D.M.

    1999-01-01

    Two different benthic phototrophic communities on tidal flats were investigated for their carbohydrate content and distribution. Carbohydrates were analysed as two operationally defined fractions, related to the difficulty of extraction from the sediment matrix. Water-soluble (colloidal) and EDTA-

  11. Environmental consequences of tidal power in a hyper-tidal muddy regime: the Severn estuary

    International Nuclear Information System (INIS)

    Kirby, R.

    1997-01-01

    Muddy hyper-tidal regimes, such as the Severn Estuary in the UK, are especially difficult for plants and animals. The difficulties stem from the semi-diurnal and semi-lunar energy fluctuations. On spring tides entrained fine sediment induces elevated suspended sediment concentrations such that photosynthesis is inhibited. On neap tides much of the entrained fine sediment is deposited on the sub-tidal bed over periods of several days to form ephemeral dense layers, which reach in excess of 100 G/l and rapidly become anaerobic on stagnation. Such occasional bed faunas as develop are characterised by very large numbers of immature individuals of a few species. One of the few organisms able to cope with the extreme conditions is the siliceous reef-building worn Sabellaria. Arising from the long term suppression in its calcareous fauna, erosion and winnowing of these Holocene clays fails to give rise to lag shell deposits, called chenier ridges, found elsewhere in eroding muddy inter-tidal systems. A tidal power barrage would shift the regime from hyper-tidal to macro-tidal decrease in turbidity would permit photosynthesis and phytoplankton growth, so stimulating the higher food chain. Ironically, perhaps, cleaning up the sewage discharges in the estuary, in the absence of barrage construction would lead to a wading bird crash whereas barrage construction would lead to an improved carrying capacity. (author)

  12. Spatially resolved synchrotron radiation induced X-ray fluorescence analyses of rare Rembrandt silverpoint drawings

    International Nuclear Information System (INIS)

    Reiche, I.; Radtke, M.; Berger, A.; Goerner, W.; Merchel, S.; Riesemeier, H.; Bevers, H.

    2006-01-01

    New analyses of a series of very rare silverpoint drawings that were executed by Rembrandt Harmensz. van Rijn (1606-1669) which are kept today in the Kupferstichkabinett (Museum of Prints and Drawings) of the State Museums of Berlin are reported here. Analysis of these drawings requires particular attention because the study has to be fully non-destructive and extremely sensitive. The metal alloy on the paper does not exceed some hundreds of μg/cm 2 . Therefore, synchrotron radiation induced X-ray fluorescence (SR-XRF) is - together with external micro-proton-induced X-ray emission - the only well-suited method for the analyses of metalpoint drawings. In some primary work, about 25 German and Flemish metalpoint drawings were investigated using spatially resolved SR-XRF analysis at the BAMline at BESSY. This study enlarges the existing French-German database of metalpoint drawings dating from the 15th and 16th centuries, as these Rembrandt drawings originate from the 17th century where this graphical technique was even rarer and already obsolete. It also illustrates how SR-XRF analysis can reinforce art historical assumptions on the dating of drawings and their connection. (orig.)

  13. Transcriptomic analyses reveal species-specific light-induced anthocyanin biosynthesis in chrysanthemum.

    Science.gov (United States)

    Hong, Yan; Tang, Xingjiao; Huang, He; Zhang, Yuan; Dai, Silan

    2015-03-17

    The flower colour of agricultural products is very important for their commercial value, which is mainly attributed to the accumulation of anthocyanins. Light is one of the key environmental factors that affect the anthocyanin biosynthesis. However, the deep molecular mechanism remains elusive, and many problems regarding the phenotypic change and the corresponding gene regulation are still unclear. In the present study, Chrysanthemum × morifolium 'Purple Reagan', a light-responding pigmentation cultivar, was selected to investigate the mechanism of light-induced anthocyanin biosynthesis using transcriptomic analyses. Only cyanidin derivatives were identified based on the analyses of the pigmentation in ray florets. Shading experiments revealed that the capitulum was the key organ and that its bud stage was the key phase responding to light. These results were used to design five libraries for transcriptomic analyses, including three capitulum developmental stages and two light conditions. RNA sequences were de novo assembled into 103,517 unigenes, of which 60,712 were annotated against four public protein databases. As many as 2,135 unigenes were differentially expressed between the light and dark libraries with 923 up-regulated and 1,212 down-regulated unigenes in response to shading. Next, interactive pathway analysis showed that the anthocyanin biosynthetic pathway was the only complete metabolic pathway both modulated in response to light and related to capitulum development. Following the shading treatment, nearly all structural genes involved in the anthocyanin biosynthetic pathway were down-regulated. Moreover, three CmMYB genes and one CmbHLH gene were identified as key transcription factors that might participate in the regulation of anthocyanin biosynthesis under light conditions based on clustering analysis and validation by RT-qPCR. Finally, a light-induced anthocyanin biosynthesis pathway in chrysanthemums was inferred. The pigmentation of the ray

  14. Coastal inlets and tidal basins

    NARCIS (Netherlands)

    De Vriend, H.J.; Dronkers, J.; Stive, M.J.F.; Van Dongeren, A.; Wang, J.H.

    2002-01-01

    lecture note: Tidal inlets and their associated basins (lagoons) are a common feature of lowland coasts all around the world. A significant part ofthe world's coastlines is formed by barrier island coasts, and most other tidal coasts are interrupted by estuaries and lagoon inlets. These tidal

  15. Net sediment transport in tidal basins: quantifying the tidal barotropic mechanisms in a unified framework

    Science.gov (United States)

    Gatto, Vincenzo Marco; van Prooijen, Bram Christiaan; Wang, Zheng Bing

    2017-11-01

    Net sediment transport in tidal basins is a subtle imbalance between large fluxes produced by the flood/ebb alternation. The imbalance arises from several mechanisms of suspended transport. Lag effects and tidal asymmetries are regarded as dominant, but defined in different frames of reference (Lagrangian and Eulerian, respectively). A quantitative ranking of their effectiveness is therefore missing. Furthermore, although wind waves are recognized as crucial for tidal flats' morphodynamics, a systematic analysis of the interaction with tidal mechanisms has not been carried out so far. We review the tide-induced barotropic mechanisms and discuss the shortcomings of their current classification for numerical process-based models. Hence, we conceive a unified Eulerian framework accounting for wave-induced resuspension. A new methodology is proposed to decompose the sediment fluxes accordingly, which is applicable without needing (semi-) analytical approximations. The approach is tested with a one-dimensional model of the Vlie basin, Wadden Sea (The Netherlands). Results show that lag-driven transport is dominant for the finer fractions (silt and mud). In absence of waves, net sediment fluxes are landward and spatial (advective) lag effects are dominant. In presence of waves, sediment can be exported from the tidal flats and temporal (local) lag effects are dominant. Conversely, sand transport is dominated by the asymmetry of peak ebb/flood velocities. We show that the direction of lag-driven transport can be estimated by the gradient of hydrodynamic energy. In agreement with previous studies, our results support the conceptualization of tidal flats' equilibrium as a simplified balance between tidal mechanisms and wave resuspension.

  16. A process study of the interaction of tidal currents, tidal mixing and density gradients in a region of freshwater influence

    Science.gov (United States)

    Xing, Jiuxing; Chen, Shengli

    2017-08-01

    A three dimensional unstructured grid model of the west coast of Britain is used to study the process of the interaction of tidal currents, tidal mixing and density gradient in the Liverpool Bay region. Calculations with M2 tidal forcing and omitting freshwater discharge show that tidal currents in the region are strong (of order 1 ms- 1), with tidal current ellipses essentially rectilinear in the surface and bottom. In the absence of tidal forcing, the freshwater is confined to a thin surface layer. With the inclusion of tidal mixing the surface layer thickens, and in the shallow water area mixed layer occupies the whole water depth. This has a significant effect of reducing its lateral spread. A detailed study of time series of velocity, salinity and turbulence reveals that at flood tide, more saline water is advected into the coastal region and rapid vertical mixing occurs, whereas at ebb tide, fresher water is advected over more saline water. The induced strong pycnocline uncouples surface and bottom layers leading to more circular tidal ellipses which rotate in opposite directions in the vertical, as found in observations. The three dimensional nature of the model reveals that this process involves both horizontal and vertical density gradients, and shows significant horizontal variability in the Liverpool Bay region.

  17. Waddenfonds Tidal Texel Demonstration project. BlueTEC Texel Tidal Project: Environmental measurement and performance analysis

    NARCIS (Netherlands)

    Ponsoni, L.; Nauw, J.J.; Smit, M.; Ober, S.; Nichols, C.; Kenkhuis, J.; Schmidt, C.; Buatois, A.; de Haas, P.

    2016-01-01

    In the context of the BlueTEC project, this report starts by introducing theBlueTEC tidal energy platform and reviewing the patterns of circulation of theMarsdiep inlet. The energy resource assessment and the site selection for theplatform's deployment are reported. This document analyses di?erent

  18. Earthquake-induced landslides from horseback surveys through GIS analyses (Sergey Soloviev Medal Lecture)

    Science.gov (United States)

    Keefer, David K.

    2010-05-01

    /hr. Accurately characterizing earthquake-induced landslides thus involves documenting many parameters during immediate post-earthquake investigations and then developing analyses to treat a wide variety of mechanisms and conditions. The generation of research up to the present has greatly increased our understanding of earthquake-induced landslides. On a regional scale we now have developed general relations between the magnitude of the triggering earthquake and several measures of landslide abundance and distribution, including numbers of landslides, areas affected by landslide occurrence, and maximum distances of landslides from the earthquake epicenters and fault ruptures. We have similar general relations between landslide occurrence and seismic intensities. We also have several empirical and analytical methods to forecast where landslides are most likely to occur in future earthquake scenarios. On the scale of individual landslides, we know much about the types of landslides specifically triggered by earthquakes and the types of slopes that produce each. We have analytical models of the main failure mechanisms, and can carry out analyses to determine whether particular slopes are likely to fail given specified future earthquake shaking. However, we still have much to learn. New remote sensing capabilities enable us to map the landslides triggered by an earthquake more completely, and GIS analyses enable us to develop much more detailed and specific relations between seismic and geologic parameters, on the one hand, and landslide occurrence on the other. Additional development and application in these areas, along with the continuing development of analytical techniques to characterize initiation and, especially, movement of landslides can be expected in the next generation of research. Such research should lead to a more detailed and specific understanding of where earthquake-induced landslides will occur and what their characteristics will be. Ultimately, this research

  19. Relativistic tidal disruption events

    Directory of Open Access Journals (Sweden)

    Levan A.

    2012-12-01

    Full Text Available In March 2011 Swift detected an extremely luminous and long-lived outburst from the nucleus of an otherwise quiescent, low luminosity (LMC-like galaxy. Named Swift J1644+57, its combination of high-energy luminosity (1048 ergs s−1 at peak, rapid X-ray variability (factors of >100 on timescales of 100 seconds and luminous, rising radio emission suggested that we were witnessing the birth of a moderately relativistic jet (Γ ∼ 2 − 5, created when a star is tidally disrupted by the supermassive black hole in the centre of the galaxy. A second event, Swift J2058+0516, detected two months later, with broadly similar properties lends further weight to this interpretation. Taken together this suggests that a fraction of tidal disruption events do indeed create relativistic outflows, demonstrates their detectability, and also implies that low mass galaxies can host massive black holes. Here, I briefly outline the observational properties of these relativistic tidal flares observed last year, and their evolution over the first year since their discovery.

  20. Relativistic tidal properties of neutron stars

    International Nuclear Information System (INIS)

    Damour, Thibault; Nagar, Alessandro

    2009-01-01

    We study the various linear responses of neutron stars to external relativistic tidal fields. We focus on three different tidal responses, associated to three different tidal coefficients: (i) a gravito-electric-type coefficient Gμ l =[length] 2l+1 measuring the lth-order mass multipolar moment GM a 1 ...a l induced in a star by an external lth-order gravito-electric tidal field G a 1 ...a l ; (ii) a gravito-magnetic-type coefficient Gσ l =[length] 2l+1 measuring the lth spin multipole moment GS a 1 ...a l induced in a star by an external lth-order gravito-magnetic tidal field H a 1 ...a l ; and (iii) a dimensionless 'shape' Love number h l measuring the distortion of the shape of the surface of a star by an external lth-order gravito-electric tidal field. All the dimensionless tidal coefficients Gμ l /R 2l+1 , Gσ l /R 2l+1 , and h l (where R is the radius of the star) are found to have a strong sensitivity to the value of the star's 'compactness'c≡GM/(c 0 2 R) (where we indicate by c 0 the speed of light). In particular, Gμ l /R 2l+1 ∼k l is found to strongly decrease, as c increases, down to a zero value as c is formally extended to the 'black hole (BH) limit'c BH =1/2. The shape Love number h l is also found to significantly decrease as c increases, though it does not vanish in the formal limit c→c BH , but is rather found to agree with the recently determined shape Love numbers of black holes. The formal vanishing of μ l and σ l as c→c BH is a consequence of the no-hair properties of black holes. This vanishing suggests, but in no way proves, that the effective action describing the gravitational interactions of black holes may not need to be augmented by nonminimal worldline couplings.

  1. Tidal dwarf galaxies in cosmological simulations

    Science.gov (United States)

    Ploeckinger, Sylvia; Sharma, Kuldeep; Schaye, Joop; Crain, Robert A.; Schaller, Matthieu; Barber, Christopher

    2018-02-01

    The formation and evolution of gravitationally bound, star forming substructures in tidal tails of interacting galaxies, called tidal dwarf galaxies (TDG), has been studied, until now, only in idealized simulations of individual pairs of interacting galaxies for pre-determined orbits, mass ratios and gas fractions. Here, we present the first identification of TDG candidates in fully cosmological simulations, specifically the high-resolution simulations of the EAGLE suite. The finite resolution of the simulation limits their ability to predict the exact formation rate and survival time-scale of TDGs, but we show that gravitationally bound baryonic structures in tidal arms already form in current state-of-the-art cosmological simulations. In this case, the orbital parameter, disc orientations as well as stellar and gas masses and the specific angular momentum of the TDG forming galaxies are a direct consequence of cosmic structure formation. We identify TDG candidates in a wide range of environments, such as multiple galaxy mergers, clumpy high-redshift (up to z = 2) galaxies, high-speed encounters and tidal interactions with gas-poor galaxies. We present selection methods, the properties of the identified TDG candidates and a road map for more quantitative analyses using future high-resolution simulations.

  2. Elemental analyses and determination of lead content in kohl (stone) by laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Haider, Abul Fazal Mohammed Yusuf; Lubna, Rebeka Sultana; Abedin, Kazi Monowar

    2012-04-01

    Elemental analyses of kohl (stone) samples collected from three different parts of the world were performed using laser-induced breakdown spectroscopy (LIBS). The analyses indicated that lead (Pb), copper (Cu), silver (Ag), iron (Fe), calcium (Ca), aluminum (Al), silicon (Si), and sodium (Na) were present in all the kohl samples. In addition to these elements, the sample from Madina, Kingdom of Saudi Arabia (KSA), contained the elements tin (Sn), zirconium (Zr), and antimony (Sb). The sample from Mount Toor, Egypt, also contained Sn. Also, quantitative analysis for lead was carried out by the standard addition method using the LIBS technique. The result showed the presence of 14.12 ± 0.28% by weight of Pb in the sample from Madina, which compares well with the measurement done using atomic absorption spectroscopy (AAS) (13.31 ± 0.46%). The standard addition method used three calibration curves drawn for three emission lines of the LIBS spectra of Pb. The limits of detection (LoD) for these calibration curves varied from 0.27% to 1.16% by weight. The lead contents of the samples from Mount Toor and the local market of Bangladesh were also measured by the AAS technique, and the results were 14.61 ± 0.48% and 8.98 ± 0.35% by weight, respectively. The reason for determining only the lead content in kohl, which may be used as an eye cosmetic, is the adverse effect that lead has on health. © 2012 Society for Applied Spectroscopy

  3. Prehospital tidal volume influences hospital tidal volume: A cohort study.

    Science.gov (United States)

    Stoltze, Andrew J; Wong, Terrence S; Harland, Karisa K; Ahmed, Azeemuddin; Fuller, Brian M; Mohr, Nicholas M

    2015-06-01

    The purposes of the study are to describe current practice of ventilation in a modern air medical system and to measure the association of ventilation strategy with subsequent ventilator care and acute respiratory distress syndrome (ARDS). Retrospective observational cohort study of intubated adult patients (n = 235) transported by a university-affiliated air medical transport service to a 711-bed tertiary academic center between July 2011 and May 2013. Low tidal volume ventilation was defined as tidal volumes less than or equal to 8 mL/kg predicted body weight. Multivariable regression was used to measure the association between prehospital tidal volume, hospital ventilation strategy, and ARDS. Most patients (57%) were ventilated solely with bag valve ventilation during transport. Mean tidal volume of mechanically ventilated patients was 8.6 mL/kg predicted body weight (SD, 0.2 mL/kg). Low tidal volume ventilation was used in 13% of patients. Patients receiving low tidal volume ventilation during air medical transport were more likely to receive low tidal volume ventilation in the emergency department (P tidal volume (P = .840). Low tidal volume ventilation was rare during air medical transport. Air transport ventilation strategy influenced subsequent ventilation but was not associated with ARDS. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Tidal power: trends and developments

    International Nuclear Information System (INIS)

    1992-01-01

    This volume covers works and studies on tidal power currently being undertaken, both nationally and internationally. The 20 papers included cover the proposed Mersey barrage, the Severn estuary and several papers on the Severn barrage. The Department of Energy's continued variety of generic work on tidal power and various overseas studies carried out by other experts are also detailed, giving the reader an up to date picture of developments in tidal power worldwide. Separate abstracts have been prepared for the individual papers. (author)

  5. Resource Assessment of Tidal Current Energy in Hangzhou Bay Based on Long Term Measurement

    Science.gov (United States)

    Zhang, Feng; Dai, Chun-Ni; Xu, Xue-Feng; Wang, Chuan-Kun; Ye, Qin

    2017-05-01

    Compared with other marine renewable energy, tidal current energy benefits a lot in high energy density and good predictability. Based on the measured tidal current data in Hangzhou Bay from Nov 2012 to Oct 2012, this paper analysed temporal and spatial changes of tidal current energy in the site. It is the first time measured data of such long time been taken in tidal current energy analysis. Occurrence frequency and duration of the current of different speed are given out in the paper. According to the analysis results, monthly average power density changed a lot in different month, and installation orientation of tidal current turbine significantly affected energy acquisition. Finally, the annual average power density of tidal current energy with coefficient Cp in the site was calculated, and final output of a tidal current plant was also estimated.

  6. Magnetic fields driven by tidal mixing in radiative stars

    Science.gov (United States)

    Vidal, Jérémie; Cébron, David; Schaeffer, Nathanaël; Hollerbach, Rainer

    2018-04-01

    Stellar magnetism plays an important role in stellar evolution theory. Approximatively 10 per cent of observed main sequence (MS) and pre-main-sequence (PMS) radiative stars exhibit surface magnetic fields above the detection limit, raising the question of their origin. These stars host outer radiative envelopes, which are stably stratified. Therefore, they are assumed to be motionless in standard models of stellar structure and evolution. We focus on rapidly rotating, radiative stars which may be prone to the tidal instability, due to an orbital companion. Using direct numerical simulations in a sphere, we study the interplay between a stable stratification and the tidal instability, and assess its dynamo capability. We show that the tidal instability is triggered regardless of the strength of the stratification (Brunt-Väisälä frequency). Furthermore, the tidal instability can lead to both mixing and self-induced magnetic fields in stably stratified layers (provided that the Brunt-Väisälä frequency does not exceed the stellar spin rate in the simulations too much). The application to stars suggests that the resulting magnetic fields could be observable at the stellar surfaces. Indeed, we expect magnetic field strengths up to several Gauss. Consequently, tidally driven dynamos should be considered as a (complementary) dynamo mechanism, possibly operating in radiative MS and PMS stars hosting orbital companions. In particular, tidally driven dynamos may explain the observed magnetism of tidally deformed and rapidly rotating Vega-like stars.

  7. Diurnal, semidiurnal, and fortnightly tidal components in orthotidal proglacial rivers.

    Science.gov (United States)

    Briciu, Andrei-Emil

    2018-02-22

    The orthotidal rivers are a new concept referring to inland rivers influenced by gravitational tides through the groundwater tides. "Orthotidal signals" is intended to describe tidal signals found in inland streamwaters (with no oceanic input); these tidal signals were locally generated and then exported into streamwaters. Here, we show that orthotidal signals can be found in proglacial rivers due to the gravitational tides affecting the glaciers and their surrounding areas. The gravitational tides act on glacier through earth and atmospheric tides, while the subglacial water is affected in a manner similar to the groundwater tides. We used the wavelet analysis in order to find tidally affected streamwaters. T_TIDE analyses were performed for discovering the tidal constituents. Tidal components with 0.95 confidence level are as follows: O1, PI1, P1, S1, K1, PSI1, M2, T2, S2, K2, and MSf. The amplitude of the diurnal tidal constituents is strongly influenced by the daily thermal cycle. The average amplitude of the semidiurnal tidal constituents is less altered and ranges from 0.0007 to 0.0969 m. The lunisolar synodic fortnightly oscillation, found in the time series of the studied river gauges, is a useful signal for detecting orthotidal rivers when using noisier data. The knowledge of the orthotidal oscillations is useful for modeling fine resolution changes in rivers.

  8. 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.

  9. 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 magnetic field generation by tidal ocean flow. We predict the motionally induced magnetic fields for the six major tidal constituents and compare their amplitudes with the spectra of night time observatory and satellite magnetic measurements for the Indian Ocean. The magnetic variations at the solar S2, K1...

  10. Anticorrosion and halobios control for tidal power generating units

    International Nuclear Information System (INIS)

    Shen, J C; Ding, L X

    2012-01-01

    The anticorrosion and halobios control is the key techniquesrelated to the safety and durability of tidal power generating units. The technique of material application, antifouling coating and cathodic protection are often adopted. The technical research, application, updating and development are carried on Jiangxia Tidal Power Station, which is based on the old Unit 1-Unit 5 operated for nearly 30 years, and the new Unit 6 operated in 2007. It is found that stainless steeland the antifouling coating used in Unit 1- Unit 5 are very effective, but cathodic protection is often likely to fail because of the limitation of structure and installation. Analyses and studies for anticorrosion and halobios control techniques of tidal power generating units according to theory, experience and actual effects have been done, which can be for reference to the tidal power station designers and builders.

  11. Sedimentary structures of tidal flats

    Indian Academy of Sciences (India)

    Sedimentary structures of some coastal tropical tidal flats of the east coast of India, and inner estuarine tidal point bars located at 30 to 50 kilometers inland from the coast, have been extensively studied under varying seasonal conditions. The results reveal that physical features such as flaser bedding, herringbone ...

  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 magnetic field generation by tidal ocean flow. We predict the motionally induced magnetic fields for the six major tidal constituents and compare their amplitudes with the spectra of night time observatory and satellite magnetic measurements for the Indian Ocean. The magnetic variations at the solar S2, K1......, 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. Tidal energy in France

    International Nuclear Information System (INIS)

    Lemperiere, F.

    2010-01-01

    The author first discusses the potential theoretical production of tidal energy in the world and more particularly in France, and compares this potential production with that of hydroelectric energy. He discusses the existence of potentially interesting sites in France in terms of sizing and exploitation modes. He describes the main associated works for turbines and sea walls, impacts on the environment, on the economy and on employment. He discusses the production possibilities and their cost, and the issue of energy storage. He indicates sites which could be built before 2025: Saint-Brieuc, Portbail-Coutainville or Granville, Mers or Cayeux, Penly or Saint-Valery en Caux. For each of this site, the author describes the project implantation, gives an gross assessment of the construction cost, and therefore of the kWh cost

  14. Tidal energy extraction: renewable, sustainable and predictable.

    Science.gov (United States)

    Nicholls-Lee, R F; Turnock, S R

    2008-01-01

    The tidal flow of sea water induced by planetary motion is a potential source of energy if suitable systems can be designed and operated in a cost-effective manner This paper examines the physical origins of the tides and how the local currents are influenced by the depth of the seabed and presence of land mass and associated coastal features. The available methods of extracting energy from tidal movement are classified into devices that store and release potential energy and those that capture kinetic energy directly. A survey is made of candidate designs and, for the most promising, the likely efficiency of energy conversion and methods of installing them are considered. Overall, the need to reduce CO2 emissions, a likely continued rise in fossil fuel cost will result in a significantly increased use of tidal energy. What is still required, especially for kinetic energy devices, is a much greater understanding of how they can be designed to withstand long-term immersion in the marine environment.

  15. Dynamical and photometric models of star formation in tidal tails

    International Nuclear Information System (INIS)

    Wallin, J.F.

    1990-01-01

    An investigation into the causes of star formation in tidal tails has been conducted using a restricted three-body dynamical model in conjunction with a broadband photometric evolutionary code. Test particles are initially placed in circular orbits around a softened point mass and then perturbed by a companion passing in a parabotic orbit. During the passage, the density evolution of the galaxy is examined both in regions within the disk and in selected comoving regions in the tidal features. Even without the inclusion of self-gravity and hydrodynamics, regions of compression form inside the disk, along the tidal tail, and in the tidal bridge causing local density increases of up to 500 percent. By assuming that the density changes relate to the star-formation rate via a Schmidt (1959) law, limits on the density changes needed to make detectable changes in the colors are calculated. A spiral galaxy population is synthesized and the effects of modest changes in the star-formation rate are explored using a broadband photometric evolutionary code. Density changes similar to those found in the dynamical models will cause detectable changes in the colors of a stellar population. From these models, it is determined that the blue colors and knotty features observed in the tidal features of some galaxies result from increased rates of star formation induced by tidally produced density increases. Limitations of this model are discussed along with photometric evolutionary models based on the density evolution in the tails. 52 refs

  16. Tidal pumping facilitates dissimilatory nitrate reduction in intertidal marshes

    Science.gov (United States)

    Zheng, Yanling; Hou, Lijun; Liu, Min; Liu, Zhanfei; Li, Xiaofei; Lin, Xianbiao; Yin, Guoyu; Gao, Juan; Yu, Chendi; Wang, Rong; Jiang, Xiaofen

    2016-01-01

    Intertidal marshes are alternately exposed and submerged due to periodic ebb and flood tides. The tidal cycle is important in controlling the biogeochemical processes of these ecosystems. Intertidal sediments are important hotspots of dissimilatory nitrate reduction and interacting nitrogen cycling microorganisms, but the effect of tides on dissimilatory nitrate reduction, including denitrification, anaerobic ammonium oxidation and dissimilatory nitrate reduction to ammonium, remains unexplored in these habitats. Here, we use isotope-tracing and molecular approaches simultaneously to show that both nitrate-reduction activities and associated functional bacterial abundances are enhanced at the sediment-tidal water interface and at the tide-induced groundwater fluctuating layer. This pattern suggests that tidal pumping may sustain dissimilatory nitrate reduction in intertidal zones. The tidal effect is supported further by nutrient profiles, fluctuations in nitrogen components over flood-ebb tidal cycles, and tidal simulation experiments. This study demonstrates the importance of tides in regulating the dynamics of dissimilatory nitrate-reducing pathways and thus provides new insights into the biogeochemical cycles of nitrogen and other elements in intertidal marshes. PMID:26883983

  17. Tidal energy site - Tidal energy site mammal/bird survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A vessel-based line visual transect survey was conducted for birds and marine mammals near the proposed Snohomish County PUD Admiralty Inlet tidal energy site...

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

    International Nuclear Information System (INIS)

    Crockett, R.G.M.; Phillips, P.S.; Gillmore, G.K.; Denman, A.R.; Groves-Kirkby, C.J.

    2006-01-01

    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 correlation 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

  19. 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...... was several times higher than net sedimentation. We propose that tidal channel sediment is bleached either on the tidal flat before it is transported to the tidal channels and incorporated in channel-fill successions or, alternatively, on the shallow intertidal part of the channel banks. Based...

  20. 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...

  1. Comparative analyses reveal different consequences of two oxidative stress inducers, gamma irradiation and potassium tellurite, in the extremophile Deinococcus radiodurans

    International Nuclear Information System (INIS)

    Narasimha, Anaganti; Basu, Bhakti; Apte, Shree Kumar

    2014-01-01

    Proteomic and mass spectrometric analyses revealed differential responses of D. radiodurans to two oxidative stressors. While both elicited oxidative stress alleviation response, major divergence was observed at the level of DNA repair, metabolic pathways and protein homeostasis. Response to gamma irradiation was focused on DNA repair and ROS scavenging but supported metabolism as well as protein homeostasis. Tellurite, induced oxidative stress alleviation but decreased reducing affected and adversely affected metabolism and protein homeostasis

  2. Identification of molecular mechanisms of radiation-induced vascular damage in normal tissues using microarray analyses

    International Nuclear Information System (INIS)

    Kruse, J.J.C.M.; Te Poele, J.A.M.; Russell, N.S.; Boersma, L.J.; Stewart, F.A.

    2003-01-01

    Radiation-induced telangiectasia, characterized by thin-walled dilated blood vessels, can be a serious late complication in patients that have been previously treated for cancer. It might cause cosmetic problems when occurring in the skin, and excessive bleeding requiring surgery when occurring in rectal mucosa. The mechanisms underlying the development of radiation-induced telangiectasia are unclear. The aim of the present study is to determine whether microarrays are useful for studying mechanisms of radiation-induced telangiectasia. The second aim is to test the hypotheses that telangiectasia is characterized by a final common pathway in different tissues. Microarray experiments were performed using amplified RNA from (sham)irradiated mouse tissues (kidney, rectum) at different intervals (1-30 weeks) after irradiation. After normalization procedures, the differentially expressed genes were identified. Control/repeat experiments were done to confirm that the observations were not artifacts of the array procedure. The mouse kidney experiments showed significant upregulation of 31 and 42 genes and downregulation of 9 and 4 genes at 10 and 20 weeks after irradiation, respectively. Irradiated mouse rectum has 278 upregulated and 537 downregulated genes at 10 weeks and 86 upregulated and 29 downregulated genes at 20 weeks. During the development of telangiectasia, 19 upregulated genes and 5 downregulated genes were common to both tissues. Upregulation of Jagged-1, known to play a role in angiogenesis, is particularly interesting in the context of radiation-induced telangiectasia. Microarrays are affective discovery tools to identify novel genes of interest, which may be involved in radiation-induced normal tissue injury. Using information from control arrays (particularly straight color, color reverse and self-self experiments) allowed for a more accurate and reproducible identification of differentially expressed genes than the selection of an arbitrary 2-fold change

  3. Hyperspectral solar-induced chlorophyll fluorescence of urban tree leaves: Analyses and applications

    Science.gov (United States)

    Van Wittenberghe, Shari

    Solar energy is the primary energy source for life on Earth which is converted into chemical energy through photosynthesis by plants, algae and cyanobacteria, releasing fuel for the organisms' activities. To dissipate excess of absorbed light energy, plants emit chlorophyll (Chl) fluorescence (650-850 nm) from the same location where photosynthesis takes place. Hence, it provides information on the efficiency of primary energy conversion. From this knowledge, many applications on vegetation and crop stress monitoring could be developed, a necessity for our planet under threat of a changing global climate. Even though the Chl fluorescence signal is weak against the intense reflected radiation background, methods for retrieving the solar-induced Chl fluorescence have been refined over the last years, both at leaf and airborne scale. However, a lack of studies on solar-induced Chl fluorescence gives difficulties for the interpretation of the signal. Within this thesis, hyperspectral upward and downward solar-induced Chl fluorescence is measured at leaf level. Fluorescence yield (FY) is calculated as well as different ratios characterizing the emitted Chl fluorescence shape. The research in this PhD dissertation illustrates the influence of several factors on the solar-induced Chl fluorescence signal. For instance, both the intensity of FY and its spectral shape of urban tree leaves are able to change under influence of stress factors such as traffic air pollution. This shows how solar-induced Chl fluorescence could function as an early stress indicator for vegetation. Further, it is shown that the signal contains information on the ultrastructure of the photosynthetic apparatus. Also, it is proven that the leaf anatomical structure and related light scattering properties play a role in the partitioning between upward and downward Chl fluorescence emission. All these findings indicate how the Chl fluorescence spectrum is influenced by factors which also influence

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

    International Nuclear Information System (INIS)

    Timperi, A.; Paettikangas, T.; Calonius, K.; Tuunanen, J.; Poikolainen, J.; Saarenheimo, A.

    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)

  5. Remnants of strong tidal interactions

    International Nuclear Information System (INIS)

    Mcglynn, T.A.

    1990-01-01

    This paper examines the properties of stellar systems that have recently undergone a strong tidal shock, i.e., a shock which removes a significant fraction of the particles in the system, and where the shocked system has a much smaller mass than the producer of the tidal field. N-body calculations of King models shocked in a variety of ways are performed, and the consequences of the shocks are investigated. The results confirm the prediction of Jaffe for shocked systems. Several models are also run where the tidal forces on the system are constant, simulating a circular orbit around a primary, and the development of tidal radii under these static conditions appears to be a mild process which does not dramatically affect material that is not stripped. The tidal radii are about twice as large as classical formulas would predict. Remnant density profiles are compared with a sample of elliptical galaxies, and the implications of the results for the development of stellar populations and galaxies are considered. 38 refs

  6. The economics of tidal energy

    International Nuclear Information System (INIS)

    Denny, Eleanor

    2009-01-01

    Concern over global climate change has led policy makers to accept the importance of reducing greenhouse gas emissions. This in turn has led to a large growth in clean renewable generation for electricity production. Much emphasis has been on wind generation as it is among the most advanced forms of renewable generation, however, its variable and relatively unpredictable nature result in increased challenges for electricity system operators. Tidal generation on the other hand is almost perfectly forecastable and as such may be a viable alternative to wind generation. This paper calculates the break-even capital cost for tidal generation on a real electricity system. An electricity market model is used to determine the impact of tidal generation on the operating schedules of the conventional units on the system and on the resulting cycling costs, emissions and fuel savings. It is found that for tidal generation to produce positive net benefits for the case study, the capital costs would have to be less than Euro 510,000 per MW installed which is currently an unrealistically low capital cost. Thus, it is concluded that tidal generation is not a viable option for the case system at the present time.

  7. Tidal effects on stellar activity

    Science.gov (United States)

    Poppenhaeger, K.

    2017-10-01

    The architecture of many exoplanetary systems is different from the solar system, with exoplanets being in close orbits around their host stars and having orbital periods of only a few days. We can expect interactions between the star and the exoplanet for such systems that are similar to the tidal interactions observed in close stellar binary systems. For the exoplanet, tidal interaction can lead to circularization of its orbit and the synchronization of its rotational and orbital period. For the host star, it has long been speculated if significant angular momentum transfer can take place between the planetary orbit and the stellar rotation. In the case of the Earth-Moon system, such tidal interaction has led to an increasing distance between Earth and Moon. For stars with Hot Jupiters, where the orbital period of the exoplanet is typically shorter than the stellar rotation period, one expects a decreasing semimajor axis for the planet and enhanced stellar rotation, leading to increased stellar activity. Also excess turbulence in the stellar convective zone due to rising and subsiding tidal bulges may change the magnetic activity we observe for the host star. I will review recent observational results on stellar activity and tidal interaction in the presence of close-in exoplanets, and discuss the effects of enhanced stellar activity on the exoplanets in such systems.

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

    Science.gov (United States)

    Peng, Ren; Hou, Yujing; Zhan, Liangtong; Yao, Yangping

    2016-01-01

    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. PMID:26771627

  9. Application of proton-induced X-ray emission technique to gunshot residue analyses

    Energy Technology Data Exchange (ETDEWEB)

    Sen, P.; Panigrahi, N.; Rao, M.S.; Varier, K.M.; Sen, S.; Mehta, G.K.

    1982-04-01

    The proton-induced X-ray emission (PIXE) technique was applied to the identification and analysis of gunshot residues. Studies were made of the type of bullet and bullet hole identification, firearm discharge element profiles, the effect of various target backings, and hand swabbings. The discussion of the results reviews the sensitivity of the PIXE technique, its nondestructive nature, and its role in determining the distance from the gun to the victim and identifying the type of bullet used and whether a wound was made by a bullet or not. The high sensitivity of the PIXE technique, which is able to analyze samples as small as 0.1 to 1 ng, and its usefulness for detecting a variety of elements should make it particularly useful in firearms residue investigations.

  10. 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.

  11. Coupled DEM-CFD analyses of landslide-induced debris flows

    CERN Document Server

    Zhao, Tao

    2017-01-01

    This book reflects the latest research results in computer modelling of landslide-induced debris flows. The book establishes an understanding of the initiation and propagation mechanisms of landslides by means of numerical simulations, so that mitigation strategies to reduce the long-term losses from landslide hazards can be devised. In this context, the book employs the Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) to investigate the mechanical and hydraulic behaviour of granular materials involved in landslides – an approach that yields meaningful insights into the flow mechanisms, concerning e.g. the mobilization of sediments, the generation and dissipation of excess pore water pressures, and the evolution of effective stresses. As such, the book provides valuable information, useful methods and robust numerical tools that can be successfully applied in the field of debris flow research.

  12. Theoretical analyses on a flipping mechanism of UV-induced DNA damage

    Science.gov (United States)

    Sato, Ryuma; Harada, Ryuhei; Shigeta, Yasuteru

    2016-01-01

    As for UV-induced DNA damage, which may induce skin cancer in animals and growth inhibition in plants, there are two types of photoproducts, namely cis-sin cyclobutane pyrimidine dimers (CPD) and pyrimidine-pyrimidone (6-4) photoproducts. When they are to be repaired, base-flipping occurs, and they bind to enzymes. However, this process remains relatively unknown at a molecular level. We analyze conformation and interaction energy changes upon base-flipping using classical molecular dynamics (CMD) simulations and ab initio electronic structure calculations. CMD simulations starting with a CPD in the flipped-in and flipped-out states showed that both states were unchanged for 500 ns, indicating the flipped-in and flipped-out processes do not occur spontaneously (without any help of the enzyme) after photo-damage. To deeply understand the reasons, we investigated interaction energy changes among bases upon structure changes during the flipped-in and flipped-out processes using Parallel Cascade Selection-MD (PaCS-MD) simulations at 400 K, followed by a fragment molecular orbital (FMO) method. The total inter-fragment interaction energy (IFIE) between CPD and other bases at the flipped-in state is estimated to be −60.08 kcal/mol. In particular, four bases strongly interact with CPD with interaction energies being −10.96, −13.70, −21.52, and −14.46 kcal/mol each. On the other hand, the total IFIE at the obtained flipped-out state increased to −10.40 kcal/mol by partly losing hydrogen bonds and π-π stacking interactions, respectively. These results clearly indicate that the base-flipping process of DNA lesions occurs with the help of external forces like interactions with appropriate enzymes such as photolyases. PMID:28409083

  13. 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

  14. Real-time images of tidal recruitment using lung ultrasound.

    Science.gov (United States)

    Tusman, Gerardo; Acosta, Cecilia M; Nicola, Marco; Esperatti, Mariano; Bohm, Stephan H; Suarez-Sipmann, Fernando

    2015-12-01

    Ventilator-induced lung injury is a form of mechanical damage leading to a pulmonary inflammatory response related to the use of mechanical ventilation enhanced by the presence of atelectasis. One proposed mechanism of this injury is the repetitive opening and closing of collapsed alveoli and small airways within these atelectatic areas-a phenomenon called tidal recruitment. The presence of tidal recruitment is difficult to detect, even with high-resolution images of the lungs like CT scan. The purpose of this article is to give evidence of tidal recruitment by lung ultrasound. A standard lung ultrasound inspection detected lung zones of atelectasis in mechanically ventilated patients. With a linear probe placed in the intercostal oblique position. We observed tidal recruitment within atelectasis as an improvement in aeration at the end of inspiration followed by the re-collapse at the end of expiration. This mechanism disappeared after the performance of a lung recruitment maneuver. Lung ultrasound was helpful in detecting the presence of atelectasis and tidal recruitment and in confirming their resolution after a lung recruitment maneuver.

  15. Tidal variations of earth rotation

    Science.gov (United States)

    Yoder, C. F.; Williams, J. G.; Parke, M. E.

    1981-01-01

    The periodic variations of the earths' rotation resulting from the tidal deformation of the earth by the sun and moon were rederived including terms with amplitudes of 0.002 millisec and greater. The series applies to the mantle, crust, and oceans which rotate together for characteristic tidal periods; the scaling parameter is the ratio of the fraction of the Love number producing tidal variations in the moment of inertia of the coupled mantle and oceans (k) to the dimensionless polar moment of inertia of the coupled moments (C). The lunar laser ranging data shows that k/C at monthly and fortnightly frequencies equals 0.99 + or - 0.15 and 0.99 + or - 0.20 as compared to the theoretical value of 0.94 + or - 0.04.

  16. Detection of local inflammation induced by repeated exposure to contact allergens by use of IVIS SpectrumCT analyses

    DEFF Research Database (Denmark)

    Nielsen, Morten M.; Schmidt, Jonas D.; Christensen, Jan P.

    2017-01-01

    Background: Contact allergy is characterized by local skin inflammation that, in some cases, can result in systemic immune activation. Objectives: To investigate whether IVIS SpectrumCT analyses can be used to detect the immune response induced by contact allergens. Methods: Mice were repeatedly...... exposed to vehicle or allergens on the ears. The local and systemic responses were analysed at different times with the ProSense 750 FAST probe in IVIS SpectrumCT measurements. In addition, changes in ear thickness, cytokine profile in the skin and immunological phenotype in the draining lymph nodes...... and spleen were determined. Results: Local inflammation was detected by ProSense 750 FAST and correlated with changes in ear thickness, cytokine profile and immunological phenotype following exposure to the strong contact allergen 2,4-dinitrofluorobenzene. Analysis of the systemic response with ProSense 750...

  17. Nanometer-resolved chemical analyses of femtosecond laser-induced periodic surface structures on titanium

    Science.gov (United States)

    Kirner, Sabrina V.; Wirth, Thomas; Sturm, Heinz; Krüger, Jörg; Bonse, Jörn

    2017-09-01

    The chemical characteristics of two different types of laser-induced periodic surface structures (LIPSS), so-called high and low spatial frequency LIPSS (HSFL and LSFL), formed upon irradiation of titanium surfaces by multiple femtosecond laser pulses in air (30 fs, 790 nm, 1 kHz), are analyzed by various optical and electron beam based surface analytical techniques, including micro-Raman spectroscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. The latter method was employed in a high-resolution mode being capable of spatially resolving even the smallest HSFL structures featuring spatial periods below 100 nm. In combination with an ion sputtering technique, depths-resolved chemical information of superficial oxidation processes was obtained, revealing characteristic differences between the two different types of LIPSS. Our results indicate that a few tens of nanometer shallow HSFL are formed on top of a ˜150 nm thick graded superficial oxide layer without sharp interfaces, consisting of amorphous TiO2 and partially crystallized Ti2O3. The larger LSFL structures with periods close to the irradiation wavelength originate from the laser-interaction with metallic titanium. They are covered by a ˜200 nm thick amorphous oxide layer, which consists mainly of TiO2 (at the surface) and other titanium oxide species of lower oxidation states underneath.

  18. Analysing the influence of different street vegetation on traffic-induced particle dispersion using microscale simulations.

    Science.gov (United States)

    Wania, Annett; Bruse, Michael; Blond, Nadège; Weber, Christiane

    2012-02-01

    Urban vegetation can be viewed as compensation to the environmental drawbacks of urbanisation. However, its ecosystem function is not well-known and, for urban planning, vegetation is mainly considered as an element of urban design. This article argues that planning practice needs to re-examine the impact of vegetation cover in the urban fabric given our evaluation of vegetation's effects on air quality, including the dispersion of traffic-induced particles at street level. Using the three-dimensional microclimate model ENVI-met®, we evaluate these effects regarding the height-to-width ratio of streets flanked by buildings and the vertical and horizontal density of street vegetation. Our results reveal vegetation's effect on particle dispersion through its influence on street ventilation. In general, vegetation was found to reduce wind speed, causing inhibition of canyon ventilation and, consequently, an increase in particle concentrations. Vegetation was also found to reduce wind speed at crown-height and to disrupt the flow field in close vicinity to the canopy. With increasing height-to-width ratio of street canyons, wind speed reduction increases and the disturbance of the flow impacts across a canyon's entire width. We also found that the effect is more pronounced in configurations with poor ventilation, such as the low wind speed, perpendicular inflow direction, and in deep canyons cases. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. 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.

  20. Properties of active tidal bedforms

    DEFF Research Database (Denmark)

    Winter, Christian; Lefebvre, Alice; Becker, Marius

    2016-01-01

    Bedforms of various shapes and sizes are ubiquitous in tidal channels, inlets and estuaries. They constitute a form roughness which has a large scale effect on the hydrodynamics and sediment transport of coastal environments. It has been shown that this form roughness can be expressed in terms...... of the lee side slope of bedforms. This study compiles data on the topography and hydraulics of compound dunes from different settings in the German Bight to discuss implications of a critical lee slope in tidal environments with reversing flow. Data from the Weser estuary is used to exemplify and quantify...

  1. 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

  2. Geometry and dynamics of a tidally deformed black hole

    International Nuclear Information System (INIS)

    Poisson, Eric; Vlasov, Igor

    2010-01-01

    The metric of a nonrotating black hole deformed by a tidal interaction is calculated and expressed as an expansion in the strength of the tidal coupling. The expansion parameter is the inverse length scale R -1 , where R is the radius of curvature of the external spacetime in which the black hole moves. The expansion begins at order R -2 , and it is carried out through order R -4 . The metric is parametrized by a number of tidal multipole moments, which specify the black hole's tidal environment. The tidal moments are freely-specifiable functions of time that are related to the Weyl tensor of the external spacetime. At order R -2 the metric involves the tidal quadrupole moments E ab and B ab . At order R -3 it involves the time derivative of the quadrupole moments and the tidal octupole moments E abc and B abc . At order R -4 the metric involves the second time derivative of the quadrupole moments, the first time derivative of the octupole moments, the tidal hexadecapole moments E abcd and B abcd , and bilinear combinations of the quadrupole moments. The metric is presented in a light-cone coordinate system that possesses a clear geometrical meaning: The advanced-time coordinate v is constant on past light cones that converge toward the black hole; the angles θ and φ are constant on the null generators of each light cone; and the radial coordinate r is an affine parameter on each generator, which decreases as the light cones converge toward the black hole. The coordinates are well-behaved on the black-hole horizon, and they are adjusted so that the coordinate description of the horizon is the same as in the Schwarzschild geometry: r=2M+O(R -5 ). At the order of accuracy maintained in this work, the horizon is a stationary null hypersurface foliated by apparent horizons; it is an isolated horizon in the sense of Ashtekar and Krishnan. As an application of our results we examine the induced geometry and dynamics of the horizon, and calculate the rate at which the

  3. Turning the tide : tidal power in the UK

    OpenAIRE

    Sustainable Development Commission

    2007-01-01

    Contents: Turning the tide : tidal power in the UK -- Executive summary -- Tidal power in the UK : research report 1 : UK tidal resource assessment -- Tidal power in the UK : research report 2 : tidal technologies overview -- Tidal power in the UK : research report 3 : Severn barrage proposals -- Tidal power in the UK : research report 4 : Severn non-barrage options -- Tidal power in the UK : research report 5 : UK case studies. Summarised in the Welsh language version of the executive ...

  4. Facies architecture of heterolithic tidal deposits : The Holocene Holland Tidal Basin

    NARCIS (Netherlands)

    Donselaar, M.E.; Geel, C.R.

    2007-01-01

    The size, shape and spatial position of lithofacies types (or facies architecture) in a tidal estuarine basin are complex and therefore difficult to model. The tidal currents in the basin concentrate sand-sized sediment in a branching pattern of tidal channels and fringing tidal flats. Away from the

  5. 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...

  6. Morphodynamics of ebb-tidal deltas

    NARCIS (Netherlands)

    Ridderinkhof, W.

    2016-01-01

    Ebb-tidal deltas are bodies of sand that are located seaward of tidal inlets. The latter connect the open sea with a back-barrier basin and separate barrier islands. The morphology (e.g., sand volume, geometry, shoal formation) of ebb-tidal deltas evolves continuously, both due to natural processes

  7. Tidal energy - a technology review

    International Nuclear Information System (INIS)

    Price, R.

    1991-01-01

    The tides are caused by gravitational attraction of the sun and the moon acting upon the world's oceans. This creates a clean renewable form of energy which can in principle be tapped for the benefit of mankind. This paper reviews the status of tidal energy, including the magnitude of the resource, the technology which is available for its extraction, the economics, possible environmental effects and non-technical barriers to its implementation. Although the total energy flux of the tides is large, at about 2 TW, in practice only a very small fraction of this total potential can be utilised in the foreseeable future. This is because the energy is spread diffusely over a wide area, requiring large and expensive plant for its collection, and is often available remote from centres of consumption. The best mechanism for exploiting tidal energy is to employ estuarine barrages at suitable sites with high tidal ranges. The technology is relatively mature and components are commercially available now. Also, many of the best sites for implementation have been identified. However, the pace and extent of commercial exploitation of tidal energy is likely to be significantly influenced, both by the treatment of environmental costs of competing fossil fuels, and by the availability of construction capital at modest real interest rates. The largest projects could require the involvement of national governments if they are to succeed. (author) 8 figs., 2 tabs., 19 refs

  8. Tidal constraints on the interior of Venus

    Science.gov (United States)

    Dumoulin, C.; Tobie, G.; Verhoeven, O.; Rosenblatt, P.; Rambaux, N.

    2017-12-01

    As a prospective study for a future exploration of Venus, we compute the tidal response of Venus' interior assuming various mantle compositions and temperature profiles representative of different scenarios of Venus' formation and evolution. The mantle density and seismic velocities are modeled from thermodynamical equilibria of mantle minerals and used to predict the moment of inertia, Love numbers, and tide-induced phase lag characterizing the signature of the internal structure in the gravity field. The viscoelasticity of the mantle is parameterized using an Andrade rheology. From the models considered here, the moment of inertia lies in the range of 0.327 to 0.342, corresponding to a core radius of 2900 to 3450 km. Viscoelasticity of the mantle strongly increases the potential Love number relative to previously published elastic models. Due to the anelasticity effects, we show that the possibility of a completely solid metal core inside Venus cannot be ruled out based on the available estimate of k2 from the Magellan mission (Konopliv and Yoder, 1996). A Love number k2 lower than 0.27 would indicate the presence of a fully solid iron core, while for larger values, solutions with an entirely or partially liquid core are possible. Precise determination of the Love numbers, k2 and h2, together with an estimate of the tidal phase lag, are required to determine the state and size of the core, as well as the composition and viscosity of the mantle.

  9. 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. Copyright © 2016. Published by Elsevier Masson SAS.

  10. Tidal deformation of a slowly rotating material body: Interior metric and Love numbers

    Science.gov (United States)

    Landry, Philippe

    2017-06-01

    The metric outside a compact body deformed by a quadrupolar tidal field is universal up to its Love numbers, constants which encode the tidal response's dependence on the body's internal structure. For a nonrotating body, the deformed external geometry is characterized by the familiar gravitational Love numbers K2el and K2mag . For a slowly rotating body, these must be supplemented by rotational-tidal Love numbers, which measure the response to couplings between the body's spin and the external tidal field. By integrating the interior field equations, I find that the response of a barotropic perfect fluid to spin-coupled tidal perturbations is described by two rotational-tidal Love numbers, which I calculate explicitly for polytropes. Two other rotational-tidal Love numbers identified in prior work are found to have a fixed, universal value for all barotropes. Equipped with the complete interior solution, I calculate the amplitude of the time-varying internal currents induced by the gravitomagnetic part of the tidal field. For a typical neutron star in an equal-mass binary system, the size of the equatorial velocity perturbation is on the order of kilometers per second.

  11. Dynamic and photometric evolutionary models of tidal tails and ripples

    International Nuclear Information System (INIS)

    Wallin, J.F.

    1989-01-01

    An investigation into the causes of star formation in tidal tails has been conducted using a restricted three-body dynamical model in conjunction with a broad-band photometric evolutionary code. In these models, regions of compression form inside the disk and along the tidal tail and tidal bridge. The effects these density changes have on the colors of the tidal features are examined with a broad-band photometric evolutionary code. A spiral galaxy population is synthesized and the effects of modest changes in the star formation rate are explored. Limits on the density changes needed to make detectable changes in the colors are calculated using a Schmidt (1959) law. These models suggest that the blue colors and knotty features observed in the tidal features of some galaxies result from increased rates of star formation induced by tidally produced density increases. Limitations of this model are discussed along with photometric evolutionary models based on the density evolution in the tails. The Lynds and Toomre (1976) interpretation of ring galaxies as the natural result of a nearly head-on collision between a disk galaxy and a companion galaxy has become widely accepted. Similarly, Quinn's (1984) interpretation of the shells in elliptical galaxies as the aftermath of the cannibalization of a low-mass companion has been quite successful in accounting for the observations. Restricted three-body calculations of high inclination, low impact parameter encounters demonstrate that the shell-like ripples observed in a number of disk galaxies can also be produced as collisional artifacts from internal oscillations much as in ring galaxies

  12. 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.

  13. Tidally Induced Bars of Galaxies in Clusters

    Czech Academy of Sciences Publication Activity Database

    Lokas, E.; Ebrová, Ivana; del Pino, A.; Sybilska, A.; Athanassoula, E.; Semczuk, M.; Gajda, G.; Fouquet, S.

    2016-01-01

    Roč. 286, č. 6 (2016), 227/1-227/13 ISSN 0004-637X Institutional support: RVO:67985815 Keywords : galaxies * clusters * evolution Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.533, year: 2016

  14. Dynamical modeling of tidal streams

    International Nuclear Information System (INIS)

    Bovy, Jo

    2014-01-01

    I present a new framework for modeling the dynamics of tidal streams. The framework consists of simple models for the initial action-angle distribution of tidal debris, which can be straightforwardly evolved forward in time. Taking advantage of the essentially one-dimensional nature of tidal streams, the transformation to position-velocity coordinates can be linearized and interpolated near a small number of points along the stream, thus allowing for efficient computations of a stream's properties in observable quantities. I illustrate how to calculate the stream's average location (its 'track') in different coordinate systems, how to quickly estimate the dispersion around its track, and how to draw mock stream data. As a generative model, this framework allows one to compute the full probability distribution function and marginalize over or condition it on certain phase-space dimensions as well as convolve it with observational uncertainties. This will be instrumental in proper data analysis of stream data. In addition to providing a computationally efficient practical tool for modeling the dynamics of tidal streams, the action-angle nature of the framework helps elucidate how the observed width of the stream relates to the velocity dispersion or mass of the progenitor, and how the progenitors of 'orphan' streams could be located. The practical usefulness of the proposed framework crucially depends on the ability to calculate action-angle variables for any orbit in any gravitational potential. A novel method for calculating actions, frequencies, and angles in any static potential using a single orbit integration is described in the Appendix.

  15. Prospects for Fundy tidal power

    International Nuclear Information System (INIS)

    Clark, R.H.

    1997-01-01

    The Bay of Fundy in Canada probably possesses the most favourable conditions in the world for the exploitation of tidal energy. The results of the comprehensive investigations carried out during the past quarter-century are reviewed together with operating and environmental aspects of the modest (20 MW) Annapolis Tidal Power Station, commissioned in 1984, the primary purpose of which was to evaluate the operation of a large (7.6 m) diameter Straflo turbine unit under low heads. The results of the operating and maintenance experience for the Annapolis Station are reviewed as well as the results of the environmental/ecological studies that have been on-going in the Annapolis Basin. The tidal power investigations have shown that a 1400 MW development at the mouth of the Cumberland Basin, at the head of the bay of Fundy, is technically and economically feasible and that its output would probably be competitive with fossil-fired plants, particularly if a 'green' accounting technique were applied to such energy sources. The importance of timing, if the exploitation of this non-polluting, renewable and completely predicable source is to be used to meet the future electrical energy needs of the maritime provinces, is discussed. (author)

  16. 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.

  17. Experimental and numerical study of a flapping tidal stream generator

    Science.gov (United States)

    Kim, Jihoon; Le, Tuyen Quang; Ko, Jin Hwan; Sitorus, Patar Ebenezer; Tambunan, Indra Hartarto; Kang, Taesam

    2017-11-01

    The tidal stream turbine is one of the systems that extract kinetic energy from tidal stream, and there are several types of the tidal stream turbine depending on its operating motion. In this research, we conduct experimental and consecutive numerical analyses of a flapping tidal stream generator with a dual configuration flappers. An experimental analysis of a small-scale prototype is conducted in a towing tank, and a numerical analysis is conducted using two-dimensional computational fluid dynamics simulations with an in-house code. Through an experimental analysis conducted while varying these factors, a high applied load and a high input arm angle were found to be advantageous. In consecutive numerical investigations with the kinematics selected from the experiments, it was found that a rear-swing flapper contributes to the total amount of power more than a front-swing flapper with a distance of two times the chord length and with a 90-degree phase difference between the two. This research was a part of the project titled `R&D center for underwater construction robotics', funded by the Ministry of Oceans and Fisheries(MOF), Korea Institute of Marine Science & Technology Promotion(KIMST,PJT200539), and Pohang City in Korea.

  18. TIDAL FRICTION AND TIDAL LAGGING. APPLICABILITY LIMITATIONS OF A POPULAR FORMULA FOR THE TIDAL TORQUE

    International Nuclear Information System (INIS)

    Efroimsky, Michael; Makarov, Valeri V.

    2013-01-01

    Tidal torques play a key role in rotational dynamics of celestial bodies. They govern these bodies' tidal despinning and also participate in the subtle process of entrapment of these bodies into spin-orbit resonances. This makes tidal torques directly relevant to the studies of habitability of planets and their moons. Our work begins with an explanation of how friction and lagging should be built into the theory of bodily tides. Although much of this material can be found in various publications, a short but self-consistent summary on the topic has been lacking in the hitherto literature, and we are filling the gap. After these preparations, we address a popular concise formula for the tidal torque, which is often used in the literature, for planets or stars. We explain why the derivation of this expression, offered in the paper by Goldreich and in the books by Kaula (Equation (4.5.29)) and Murray and Dermott (Equation (4.159)), implicitly sets the time lag to be frequency independent. Accordingly, the ensuing expression for the torque can be applied only to bodies having a very special (and very hypothetical) rheology which makes the time lag frequency independent, i.e., the same for all Fourier modes in the spectrum of tide. This expression for the torque should not be used for bodies of other rheologies. Specifically, the expression cannot be combined with an extra assertion of the geometric lag being constant, because at finite eccentricities the said assumption is incompatible with the constant-time-lag condition.

  19. TIDAL FRICTION AND TIDAL LAGGING. APPLICABILITY LIMITATIONS OF A POPULAR FORMULA FOR THE TIDAL TORQUE

    Energy Technology Data Exchange (ETDEWEB)

    Efroimsky, Michael; Makarov, Valeri V., E-mail: michael.efroimsky@usno.navy.mil, E-mail: vvm@usno.navy.mil [US Naval Observatory, Washington, DC 20392 (United States)

    2013-02-10

    Tidal torques play a key role in rotational dynamics of celestial bodies. They govern these bodies' tidal despinning and also participate in the subtle process of entrapment of these bodies into spin-orbit resonances. This makes tidal torques directly relevant to the studies of habitability of planets and their moons. Our work begins with an explanation of how friction and lagging should be built into the theory of bodily tides. Although much of this material can be found in various publications, a short but self-consistent summary on the topic has been lacking in the hitherto literature, and we are filling the gap. After these preparations, we address a popular concise formula for the tidal torque, which is often used in the literature, for planets or stars. We explain why the derivation of this expression, offered in the paper by Goldreich and in the books by Kaula (Equation (4.5.29)) and Murray and Dermott (Equation (4.159)), implicitly sets the time lag to be frequency independent. Accordingly, the ensuing expression for the torque can be applied only to bodies having a very special (and very hypothetical) rheology which makes the time lag frequency independent, i.e., the same for all Fourier modes in the spectrum of tide. This expression for the torque should not be used for bodies of other rheologies. Specifically, the expression cannot be combined with an extra assertion of the geometric lag being constant, because at finite eccentricities the said assumption is incompatible with the constant-time-lag condition.

  20. Statistical and Physical Analyses of Electromigration-induced Failure in Lead-free Flip Chip Solder Joints

    Science.gov (United States)

    Choi, Daechul

    While electromigration in Al and Cu interconnects has been a persistent reliability issue in microelectronic industry, the trend of miniaturization in wireless and portable devices has caused electromigration in Pb-free flip chip solder joints to become another most challenging problem in electronic manufacturing industry. Up to now, the link between statistical and physical analyses of electromigration failure is weak, for example, we do not have a deep understanding of the reliability failure on the basis of kinetics of void nucleation and growth. In this study, we intend to make a direct link between Weibull distribution of Pb-free flip chip solder joint failure and Johnson-Mehl-Avrami's equations of phase transformations in terms of void nucleation and growth based on the assumption that void nucleation and propagation can be treated as a phase transformation induced by electromigration in the interconnect which is the main cause of failure in Pb-free solder joints. The statistical failure data from Pb-free flip chip solder joints were systematically collected by DAQ (data acquisition) program which measures in-situ resistance change due to a set of constant current densities stressed at a set of temperatures, and the data were statistically analyzed by Weibull distribution by using Minitab program. The test samples are from industry and the data are reproducible. It is worth mentioning that Weibull distribution function and Avrami's equation have the same mathematical form, and we shall develop the mathematical and physical links between them. Physical analysis of failure was supported by SEM (scanning electron microscope) examination and FIB (focused ion beam) of the cross-section of failed samples, 3-dimensional finite element simulation, and 3-D images obtained by using synchrotron radiation x-ray tomography at Advanced Light Source of Lawrence Berkeley National Laboratory. The final goal of this research is to establish a tool for critical analysis of

  1. TIDAL NOVAE IN COMPACT BINARY WHITE DWARFS

    International Nuclear Information System (INIS)

    Fuller, Jim; Lai Dong

    2012-01-01

    Compact binary white dwarfs (WDs) undergoing orbital decay due to gravitational radiation can experience significant tidal heating prior to merger. In these WDs, the dominant tidal effect involves the excitation of outgoing gravity waves in the inner stellar envelope and the dissipation of these waves in the outer envelope. As the binary orbit decays, the WDs are synchronized from outside in (with the envelope synchronized first, followed by the core). We examine the deposition of tidal heat in the envelope of a carbon-oxygen WD and study how such tidal heating affects the structure and evolution of the WD. We show that significant tidal heating can occur in the star's degenerate hydrogen layer. This layer heats up faster than it cools, triggering runaway nuclear fusion. Such 'tidal novae' may occur in all WD binaries containing a CO WD, at orbital periods between 5 minutes and 20 minutes, and precede the final merger by 10 5 -10 6 years.

  2. 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 tidal regimes over the continental shelves are often less documented due to lack of coastal water level data. This is of concern since continental shelves rule the global dissipation of tidal energy. The tides along the Southwest Indian shelf...

  3. Array Optimization for Tidal Energy Extraction in a Tidal Channel – A Numerical Modeling Analysis

    OpenAIRE

    Yang, Zhaoqing; Wang, Taiping; Copping, Andrea

    2014-01-01

    This paper presents an application of a hydrodynamic model to simulate tidal energy extraction in a tidal dominated estuary in the Pacific Northwest coast. A series of numerical experiments were carried out to simulate tidal energy extraction with different turbine array configurations, including location, spacing and array size. Preliminary model results suggest that array optimization for tidal energy extraction in a real-world site is a very complex process that requires consideration of m...

  4. Spatially resolved synchrotron-induced X-ray fluorescence analyses of metal point drawings and their mysterious inscriptions

    International Nuclear Information System (INIS)

    Reiche, Ina; Radtke, Martin; Berger, Achim; Goerner, Wolf; Ketelsen, Thomas; Merchel, Silke; Riederer, Josef; Riesemeier, Heinrich; Roth, Michael

    2004-01-01

    Synchrotron-induced X-ray fluorescence (Sy-XRF) analysis was used to study the chemical composition of precious Renaissance silverpoint drawings. Drawings by famous artists such as Albrecht Duerer (1471-1528) and Jan van Eyck (approximately 1395-1441) must be investigated non-destructively. Moreover, extremely sensitive synchrotron- or accelerator-based techniques are needed since only small quantities of silver are deposited on the paper. New criteria for attributing these works to a particular artist could be established based on the analysis of the chemical composition of the metal points used. We illustrate how analysis can give new art historical information by means of two case studies. Two particular drawings, one of Albrecht Duerer, showing a profile portrait of his closest friend, 'Willibald Pirckheimer' (1503), and a second one attributed to Jan van Eyck, showing a 'Portrait of an elderly man', often named 'Niccolo Albergati', are the object of intense art historical controversy. Both drawings show inscriptions next to the figures. Analyses by Sy-XRF could reveal the same kind of silverpoint for the Pirckheimer portrait and its mysterious Greek inscription, contrary to the drawing by Van Eyck where at least three different metal points were applied. Two different types of silver marks were found in this portrait. Silver containing gold marks were detected in the inscriptions and over-subscriptions. This is the first evidence of the use of gold points for metal point drawings in the Middle Ages

  5. Formation of double galaxies by tidal capture

    International Nuclear Information System (INIS)

    Alladin, S.M.; Potdar, A.; Sastry, K.S.

    1975-01-01

    The conditions under which double galaxies may be formed by tidal capture are considered. Estimates for the increase in the internal energy of colliding galaxies due to tidal effects are used to determine the magnitudes Vsub(cap) and Vsub(dis) of the maximum relative velocities at infinite separation required for tidal capture and tidal disruption respectively. A double galaxy will be formed by tidal capture without tidal disruption of a component if Vsub(cap)>Vsub(i) and Vsub(cap)>Vsub(dis) where Vsub(i) is the initial relative speed of the two galaxies at infinite separation. If the two galaxies are of the same dimension, formulation of double galaxies by tidal capture is possible in a close collision either if the two galaxies do not differ much in mass and density distribution or if the more massive galaxy is less centrally concentrated than the other. If it is assumed as statistics suggest, that the mass of a galaxy is proportional to the square of its radius, it follows that the probability of the formation of double galaxies by tidal capture increases with the increase in mass of the galaxies and tidal distribution does not occur in a single collision for any distance of closest approach of the two galaxies. (Auth.)

  6. Interactions Between Wetlands and Tidal Inlets

    National Research Council Canada - National Science Library

    Sanchez, Alejandro

    2008-01-01

    This Coastal and Hydraulics Engineering Technical Note (CHETN) presents numerical simulations investigating how the loss of wetlands in estuaries modifies tidal processes in inlet navigation channels...

  7. Tidal evolution of globular clusters. I - Method

    Science.gov (United States)

    Oh, K. S.; Lin, D. N. C.; Aarseth, S. J.

    1992-01-01

    Tidal evolution of globular clusters is regulated by both Galactic tidal effects and internal relaxation processes. In order to investigate the tidal evolution of globular clusters, a numerical scheme which utilizes a Fokker-Planck approach as well as direct numerical integration of the restricted three-body problem is developed. In the inner regions of the cluster, stellar orbits are mapped with the cluster's gravitational potential and orbit-averaged diffusion coefficients. In the outer regions, the Galactic tidal field is explicitly included in the direct orbital integration. This method is presented here with some tests on King-Michie models.

  8. Does elevation matter? Living foraminiferal distribution in a hyper tidal salt marsh (Canche Estuary, Northern France)

    Science.gov (United States)

    Francescangeli, F.; Bouchet, V. M. P.; Trentesaux, A.; Armynot du Chatelet, E.

    2017-07-01

    In the present study we investigate the ecology and distribution of living benthic foraminifera to test the effect of hyper tidal exposure and their suitability as sea level indicators. Within a salt marsh area along the Canche Estuary (northern France), four transects were sampled to see the effects of maximal tidal constraints (shore transects) and minimal tidal constraints (alongshore transects). Multivariate analyses have been performed to determine the correlations between biotic (foraminiferal absolute abundances) and abiotic factors (elevation, grain-size, TOC and total sulphur). For each of the principal benthic foraminiferal species the tolerance to subaerial exposure have been estimated as well. Two distinctive foraminiferal zones have been identified along the vertical tidal gradient: a zone I in the higher part of the salt marsh dominated by agglutinated and porcelaneous taxa, and a zone II in the lower one dominated by hyaline specimens. Hyper tidal exposure constraints the foraminiferal vertical zonation in accordance with the tidal frame. However it does not constitute a threshold parameter able by itself to explain all the faunal variations in the Canche Estuary. For sea level indicators, foraminifera should be considered relative to tidal subaerial exposure rather than to absolute altitude.

  9. One-dimensional Analytical Modelling of Floating Seed Dispersal in Tidal Channels

    Science.gov (United States)

    Shi, W.; Purnama, A.; Shao, D.; Cui, B.; Gao, W.

    2017-12-01

    Seed dispersal is a primary factor influencing plant community development, and thus plays a critical role in maintaining wetland ecosystem functioning. However, compared with fluvial seed dispersal of riparian plants, dispersal of saltmarsh plant seeds in tidal channels is much less studied due to its complex behavior, and relevant mathematical modelling is particularly lacking. In this study, we developed a one-dimensional advection-dispersion model to explore the patterns of tidal seed dispersal. Oscillatory tidal current and water depth were assumed to represent the tidal effects. An exponential decay coefficient λ was introduced to account for seed deposition and retention. Analytical solution in integral form was derived using Green's function and further evaluated using numerical integration. The developed model was applied to simulate Spartina densiflora seed dispersal in a tidal channel located at the Mad River Slough in North Humboldt Bay, California, USA, to demonstrate its practical applicability. Model predictions agree satisfactorily with field observation and simulation results from Delft3D numerical model. Sensitivity analyses were also conducted to evaluate the effects of varying calibrated parameters on model predictions. The range of the seed dispersion as well as the distribution of the seed concentration were further analyzed through statistical parameters such as centroid displacement and variance of the seed cloud together with seed concentration contours. Implications of the modelling results on tidal marsh restoration and protection, e.g., revegetation through seed addition, were also discussed through scenario analysis. The developed analytical model provides a useful tool for ecological management of tidal marshes.

  10. 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

  11. Tidal energy from the Wyre

    International Nuclear Information System (INIS)

    Matthews, M.E.; Young, R.M.

    1992-01-01

    Amongst the estuaries around the United Kingdom, the Wyre has been found to be prominent in possessing the main requirements for a small scale tidal energy scheme. This paper describes the results of a Preliminary Feasibility Study undertaken to assess the viability of the construction of a barrage at the mouth of the Wyre estuary by establishing the form, cost, energy output and the nature and broad scale effect that the project may have on the environment and surrounding region. The study also investigated the potential benefits of utilising the barrage as a road crossing between the town of Fleetwood and Over Wyre. (author)

  12. Effect of tidal simulations and entrainment of an endogenous tidal rhythm in a non-tidal population of Gammarus zaddachi

    NARCIS (Netherlands)

    Looijenga, Paul J.; Dieleman, Jan C.

    1980-01-01

    The activity of G. zaddachi from a non-tidal environment (the brackish lake “De Putten”, prov. North Holland, The Netherlands), has been studied in a current chamber in which tidal cycles can be simulated, in order to make a comparison with estuarine populations. The animals show a clear nocturnal

  13. 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

  14. Modeling and control of a hybrid wind-tidal turbine with hydraulic accumulator

    International Nuclear Information System (INIS)

    Fan, YaJun; Mu, AnLe; Ma, Tao

    2016-01-01

    This paper presents the modeling and control of a hybrid wind-tidal turbine with hydraulic accumulator. The hybrid turbine captures the offshore wind energy and tidal current energy simultaneously and stores the excess energy in hydraulic accumulator prior to electricity generation. Two hydraulic pumps installed respectively in wind and tidal turbine nacelles are used to transform the captured mechanical energy into hydraulic energy. To extract the maximal power from wind and tidal current, standard torque controls are achieved by regulating the displacements of the hydraulic pumps. To meet the output power demand, a Proportion Integration Differentiation (PID) controller is designed to distribute the hydraulic energy between the accumulator and the Pelton turbine. A simulation case study based on combining a 5 MW offshore wind turbine and a 1 MW tidal current turbine is undertaken. Case study demonstrates that the hybrid generation system not only captures all the available wind and tidal energy and also delivers the desired generator power precisely through the accumulator damping out all the power fluctuations from the wind and tidal speed disturbances. Energy and exergy analyses show that the energy efficiency can exceed 100% as the small input speeds are considered, and the exergy efficiency has the consistent change trends with demand power. Further more parametric sensitivity study on hydraulic accumulator shows that there is an inversely proportional relationship between accumulator and hydraulic equipments including the pump and nozzle in terms of dimensions. - Highlights: • A hybrid wind-tidal turbine is presented. • Hydraulic accumulator stores/releases the surplus energy. • Standard torque controls extract the maximal power from wind and tidal. • Generator outputs meet the electricity demand precisely. • Parametric sensitivity study on accumulator is implemented.

  15. 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...... that in some coastal regions the amplitudes of the electric field can reach 100 mV/km and 10 mV/km for M2 and O1 tides respectively. The changes of lithosphere resistance produce detectable changes in the tidal electric signals. We show that our predictions are in a good agreement with observations.......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...

  16. Kozai Cycles and Tidal Friction

    Energy Technology Data Exchange (ETDEWEB)

    L, K; P.P., E

    2009-07-17

    Several studies in the last three years indicate that close binaries, i.e. those with periods of {approx}< 3 d, are very commonly found to have a third body in attendance. We argue that this proves that the third body is necessary in order to make the inner period so short, and further argue that the only reasonable explanation is that the third body causes shrinkage of the inner period, from perhaps a week or more to the current short period, by means of the combination of Kozai cycles and tidal friction (KCTF). In addition, once KCTF has produced a rather close binary, magnetic braking also combined with tidal friction (MBTF) can decrease the inner orbit further, to the formation of a contact binary or even a merged single star. Some of the products of KCTF that have been suggested, either by others or by us, are W UMa binaries, Blue Stragglers, X-ray active BY Dra stars, and short-period Algols. We also argue that some components of wide binaries are actually merged remnants of former close inner pairs. This may include such objects as rapidly rotating dwarfs (AB Dor, BO Mic) and some (but not all) Be stars.

  17. The internal flow pattern analysis of a tidal power turbine operating on bidirectional generation-pumping

    International Nuclear Information System (INIS)

    Luo, Y Y; Xiao, Y X; Wang, Z W

    2013-01-01

    Using tidal energy can reduce environment pollution, save conventional energy and improve energy structure, hence it presents great advantage and is developing potential. Influenced by flood tide and low tide, a fully functional tidal power station needs to experience six operating modes, including bidirectional generation, pumping and sluice; the internal unsteady flow pattern and dynamic characters are very complicated. Based on a bidirectional tidal generator unit, three-dimensional unsteady flows in the flow path were calculated for four typical operating conditions with the pressure pulsation characteristics analyzed. According to the numerical results, the internal flow characteristics in the flow path were discussed. The influence of gravity to the hydraulic performance and flow characteristics were analysed. The results provide a theoretical analysis method of the hydraulic optimization design of the same type unit as well as a direction for stable operation and optimal scheduling of existing tidal power unit

  18. Morphodynamics of Hue tidal inlets, Vietnam

    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. Effects of tides, waves, river flows and system configuration on the inlet morphologies are investigated with the aid of process-based state-of-the-art numerical models.

  19. Dynamics and radiation from tidal disruption events

    NARCIS (Netherlands)

    Bonnerot, C.A.

    2017-01-01

    When a star gets too close to a supermassive black hole, it is torn apart by strong tidal forces in a tidal disruption event (TDE). The stellar matter then fuels the compact object causing a bright flare that is a unique probe of the majority of galactic nuclei, otherwise quiescent. For

  20. Tidal Freshwater Wetlands: Variation and Changes

    NARCIS (Netherlands)

    Barendregt, A.; Swarth, C.W.

    2013-01-01

    Tidal freshwater wetlands (TFW) are situated in the upper estuary in a zone bordered upstream by the nontidal river and downstream by the oligohaline region. Here, discharge of freshwater from the river and the daily tidal pulse from the sea combine to create conditions where TFW develop. TFW

  1. A preliminary study of tidal current ridges

    Science.gov (United States)

    Liu, Zhenxia; Xia, Dongxing

    1985-06-01

    Tidal current ridges, widely distributed geomorphological phenomena over the continental shelf of the world, are studied. They are formed by tidal current and the trend of their sand bodies runs parallel to the direction of tidal current. There are two types of the plane shapes: the parallel and the fingered. Conditions of forming tidal current ridges are the velocities of tidal current ranging from 1 to 3.5 knots and the supply of abundant sediments. Tidal current ridges often develop in following morphological locations: the bays, estuaries, the mouths of channels, as well as the offshore area with strong tidal current. Tidal current ridges occur generally at a water depth of less than 35 metres. The sediments of tidal current ridges are mainly composed of sand. The grain size of the sediments is uniform and well sorted. The characteristics of grain size of the sand imply that their formation mechanism is similar to that of river sand, that is, both of them are the result of flow movements in a trongth channel controlled by boundary. There is however difference between them that the river sand is formed by one-way flow movement while the tidal current sand by two-way movement. There are two saltation populations in the log-probability curves of tidal current sand, the sorting of first saltation population is better than the second one, and having positive skewness, which differs from beach sand. In the C-M grain size pattern tidal current sand is most found in graded suspension segment. The continental shelves of the Yellow Sea, the East China Sea and the South China Sea have favourable conditions for developing tidal current ridges in massive scale and special shape, such as the tidal current ridges in the offshore of Jiangsu, the Gulf of Korea, the shoal of Liaodong, the east and west mouths of the channel of Qiongzhou, Jiaozhou Bay, the shoal of Taiwan, Lingdingyang, the north branch of Changjiang estuary. The studies of them are of vital significance in

  2. Relativistic theory of tidal Love numbers

    International Nuclear Information System (INIS)

    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 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.

  3. Tidal current and tidal energy changes imposed by a dynamic tidal power system in the Taiwan Strait, China

    Science.gov (United States)

    Dai, Peng; Zhang, Jisheng; Zheng, Jinhai

    2017-12-01

    The Taiwan Strait has recently been proposed as a promising site for dynamic tidal power systems because of its shallow depth and strong tides. Dynamic tidal power is a new concept for extracting tidal potential energy in which a coast-perpendicular dike is used to create water head and generate electricity via turbines inserted in the dike. Before starting such a project, the potential power output and hydrodynamic impacts of the dike must be assessed. In this study, a two-dimensional numerical model based on the Delft3D-FLOW module is established to simulate tides in China. A dike module is developed to account for turbine processes and estimate power output by integrating a special algorithm into the model. The domain decomposition technique is used to divide the computational zone into two subdomains with grid refinement near the dike. The hydrodynamic processes predicted by the model, both with and without the proposed construction, are examined in detail, including tidal currents and tidal energy flux. The predicted time-averaged power yields with various opening ratios are presented. The results show that time-averaged power yield peaks at an 8% opening ratio. For semidiurnal tides, the flow velocity increases in front of the head of the dike and decreases on either side. For diurnal tides, these changes are complicated by the oblique incidence of tidal currents with respect to the dike as well as by bathymetric features. The dike itself blocks the propagation of tidal energy flux.

  4. Ambient Noise in an Urbanized Tidal Channel

    Science.gov (United States)

    Bassett, Christopher

    In coastal environments, when topographic and bathymetric constrictions are combined with large tidal amplitudes, strong currents (> 2 m/s) can occur. Because such environments are relatively rare and difficult to study, until recently, they have received little attention from the scientific community. However, in recent years, interest in developing tidal hydrokinetic power projects in these environments has motivated studies to improve this understanding. In order to support an analysis of the acoustic effects of tidal power generation, a multi-year study was conducted at a proposed project site in Puget Sound (WA) are analyzed at a site where peak currents exceeded 3.5 m/s. From these analyses, three noise sources are shown to dominate the observed variability in ambient noise between 0.02-30 kHz: anthropogenic noise from vessel traffic, sediment-generated noise during periods of strong currents, and flow-noise resulting from turbulence advected over the hydrophones. To assess the contribution of vessel traffic noise, one calendar year of Automatic Identification System (AIS) ship-traffic data was paired with hydrophone recordings. The study region included inland waters of the Salish Sea within a 20 km radius of the hydrophone deployment site in northern Admiralty Inlet. The variability in spectra and hourly, daily, and monthly ambient noise statistics for unweighted broadband and M-weighted sound pressure levels is driven largely by vessel traffic. Within the one-year study period, at least one AIS transmitting vessel is present in the study area 90% of the time and over 1,363 unique vessels are recorded. A noise budget for vessels equipped with AIS transponders identifies cargo ships, tugs, and passenger vessels as the largest contributors to noise levels. A simple model to predict received levels at the site based on an incoherent summation of noise from different vessel types yields a cumulative probability density function of broadband sound pressure

  5. Channel Capture as a Response to Anthropogenic Modification of a Tidal Landscape: Ganges-Brahmaputra-Meghna Delta, Southwest Bangladesh

    Science.gov (United States)

    Wilson, C.; Bain, R. L.; Goodbred, S. L., Jr.; Hale, R. P.

    2017-12-01

    Studies of tidal channel dynamics frequently emphasize "morphologically short" spatial scales (i.e., settings in which the cross-system tidal propagation time is negligible) or idealized single-channel planforms. In contrast, tides in the Ganges-Brahmaputra-Meghna Delta (GBMD) propagate more than 100 kilometers inland from the coast through a network of interconnected tidal estuaries, producing complex hydrodynamic behavior that remains poorly understood. Intense anthropogenic modification of the GBMD landscape further complicates tidally-driven, natural delta surface maintenance. Analyzing this system is particularly urgent given the current trend of rising sea level and its associated impacts on coastal communities.We present results from an ongoing field investigation of tidal waveform interaction and mass exchange between the Pussur and Shibsa Rivers, two large macrotidal estuaries in the southwestern GBMD. In the 1960s, construction of earthen embankments ("polders") eliminated regular tidal inundation for a vast region of the tidal platform, shrinking the Shibsa and Pussur basins by an estimated 1000 km2 and 700 km2, respectively. Conservation of mass predicts that a reduction in tidal basin area will decrease peak flow velocities and induce channel siltation; indeed, 100 km2 of secondary channels at the distal end of the tidal range have partly or fully closed in recent decades. The Pussur is likewise rapidly shoaling, restricting navigational access along a major shipping route. However, discharge and bathymetric datasets indicate that the adjacent Shibsa conveys three to four times more water than the Pussur and is actively scouring its bed, contrary to its predicted response to polder construction. Our field measurements are consistent with an ongoing channel capture event in which the Shibsa floods and drains a progressively greater portion of the former Pussur basin, allowing the Shibsa to widen and deepen despite the regional trend of channel

  6. 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.

  7. 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

  8. Implementation and evaluation of the International Electrotechnical Commission specification for tidal stream energy resource assessment: A case study

    International Nuclear Information System (INIS)

    Ramos, V.; Ringwood, John V.

    2016-01-01

    Highlights: • The utility of the International Electrotechnical Commission standards for tidal stream resource assessment were analysed. • The Orkney Region (N Scotland) was used as a case study. • A sensitivity analysis in terms of accuracy vs computational times was carried out for different mesh resolutions. • Modelling the operation of a tidal energy converter becomes essential for an appropriate estimation of the tidal resource. • Practical recommendations are proposed for future editions of the technical standard. - Abstract: Over the next decades, tidal stream energy aims to become a fully commercially viable energy source. For this purpose, complete knowledge regarding tidal stream resource assessment is essential. In this context, the International Electrotechnical Commission has developed a technical standard for the assessment of the tidal stream resource, “IEC 62600-201 TS: Marine energy - Wave, tidal and other water current converters - Part 201: Tidal energy resource assessment and characterisation”, offering a vast set of recommendations in the fields of data collection, numerical modelling, data analysis and reporting of the results with the purpose of standardising tidal stream resource characterisation. The standard divides resource assessments into two different classes: feasibility and layout design. The model setup procedure (mesh resolution, boundary conditions) and the computational effort required vary significantly from one class to another. For these reasons, the objective of the present work is to explore the proposed standard using the Orkney Region (N Scotland) as a case study. Overall, it was found that the standard works well, offering a detailed characterisation of the tidal resource; however, in order to improve its manageability, some aspects related to the grid resolution requirements and the approach to model a tidal energy converter could be revisited for future editions.

  9. 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

  10. Tidal Streams Near and Far

    Science.gov (United States)

    Fardal, Mark A.

    2014-06-01

    The Pandas survey of stars in M31's disk and halo is crisscrossed by numerous tidal features from both M31 and the Milky Way. Here I focus on two narrow stellar streams visible in the survey. They have comparable angular extent in the survey (10-13 degrees long versus only 0.3 degree wide), but one is a local Milky Way stream at about 30 kpc and one is in M31, roughly 25 times more distant. I estimate the stellar mass and metallicity in the streams and the distance gradient along them. The kinematics of the M31 stream is sparsely sampled by red giant stars and globular clusters. Bayesian modeling of the stream data yields accurate constraints on the orbital parameters of the streams.

  11. Atmospheric noise of a breaking tidal bore.

    Science.gov (United States)

    Chanson, Hubert

    2016-01-01

    A tidal bore is a surge of waters propagating upstream in an estuary as the tidal flow turns to rising and the flood tide propagates into a funnel-shaped system. Large tidal bores have a marked breaking roller. The sounds generated by breaking tidal bores were herein investigated in the field (Qiantang River) and in laboratory. The sound pressure record showed two dominant periods, with some similarity with an earlier study [Chanson (2009). J. Acoust. Soc. Am. 125(6), 3561-3568]. The two distinct phases were the incoming tidal bore when the sound amplitude increased with the approaching bore, and the passage of the tidal bore in front of the microphone when loud and powerful noises were heard. The dominant frequency ranged from 57 to 131 Hz in the Qiantang River bore. A comparison between laboratory and prototype tidal bores illustrated both common features and differences. The low pitch sound of the breaking bore had a dominant frequency close to the collective oscillations of bubble clouds, which could be modeled with a bubble cloud model using a transverse dimension of the bore roller. The findings suggest that this model might be over simplistic in the case of a powerful breaking bore, like that of the Qiantang River.

  12. No Snowball on Habitable Tidally Locked Planets

    Energy Technology Data Exchange (ETDEWEB)

    Checlair, Jade; Abbot, Dorian S. [Department of the Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States); Menou, Kristen, E-mail: jadecheclair@uchicago.edu [Centre for Planetary Sciences, Department of Physical and Environmental Sciences, University of Toronto at Scarborough, Toronto, ON M1C 1A4 (Canada)

    2017-08-20

    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO{sub 2} outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  13. No Snowball on Habitable Tidally Locked Planets

    Science.gov (United States)

    Checlair, Jade; Menou, Kristen; Abbot, Dorian S.

    2017-08-01

    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO2 outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  14. No Snowball on Habitable Tidally Locked Planets

    International Nuclear Information System (INIS)

    Checlair, Jade; Abbot, Dorian S.; Menou, Kristen

    2017-01-01

    The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO 2 outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.

  15. Spin Dependence in Tidal Disruption Events

    Science.gov (United States)

    Kesden, Michael; Stone, Nicholas; van Velzen, Sjoert

    2018-01-01

    A supermassive black hole (SBH) can tidally disrupt stars when its tidal field overwhelms the stars’ self-gravity. The stellar debris produced in such tidal disruption events (TDEs) evolves into tidal streams that can self-intersect. These inelastic stream collisions dissipate orbital energy, both circularizing the tidal stream and contributing to the emission observed during the TDE. Once circularized into a disk, the stellar debris can be viscously accreted by the SBH powering additional luminous emission. We explore how SBH spin can affect the tidal disruption process. Tidal forces are spin dependent, as is the minimum orbital angular momentum below which stars are directly captured by the SBH. This implies that the TDE rate will be spin dependent, particularly for more massive SBHs for which relativistic effects are more significant. SBH spin also affects TDE light curves through the initial debris orbits, the nature of the stream collisions, the viscous evolution of the accretion disk, and the possibility of launching jets. We explore the spin dependence of these phenomena to identify promising signatures for upcoming surveys expected to discover hundreds of TDE candidates in the next decade.

  16. Tidal ventilation distribution during pressure-controlled ventilation and pressure support ventilation in post-cardiac surgery patients.

    Science.gov (United States)

    Blankman, P; VAN DER Kreeft, S M; Gommers, D

    2014-09-01

    Inhomogeneous ventilation is an important contributor to ventilator-induced lung injury. Therefore, this study examines homogeneity of lung ventilation by means of electrical impedance tomography (EIT) measurements during pressure-controlled ventilation (PCV) and pressure support ventilation (PSV) using the same ventilation pressures. Twenty mechanically ventilated patients were studied after cardiac surgery. On arrival at the intensive care unit, ventilation distribution was measured with EIT just above the diaphragm for 15 min. After awakening, PCV was switched to PSV and EIT measurements were again recorded. Tidal impedance variation, a measure of tidal volume, increased during PSV compared with PCV, despite using the same ventilation pressures (P = 0.045). The distribution of tidal ventilation to the dependent lung region was more pronounced during PSV compared with PCV, especially during the first half of the inspiration. An even distribution of tidal ventilation between the dependent and non-dependent lung regions was seen during PCV at lower tidal volumes (tidal volumes (≥ 8 ml/kg). In addition, the distribution of tidal ventilation was predominantly distributed to the dependent lung during PSV at low tidal volumes. In post-cardiac surgery patients, PSV showed improved ventilation of the dependent lung region due to the contribution of the diaphragm activity, which is even more pronounced during lower assist levels. © 2014 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

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

    International Nuclear Information System (INIS)

    Kanemoto, T; Suzuki, T

    2010-01-01

    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.

  18. Tidal coupling of a Schwarzschild black hole and circularly orbiting moon

    International Nuclear Information System (INIS)

    Fang Hua; Lovelace, Geoffrey

    2005-01-01

    We describe the possibility of using the laser interferometer space antenna (LISA) 's gravitational-wave observations to study, with high precision, the response of a massive central body (e.g. a black hole or a soliton star) to the tidal gravitational pull of an orbiting, compact, small-mass object (a white dwarf, neutron star, or small-mass black hole). Motivated by this LISA application, we use first-order perturbation theory to study tidal coupling for a special, idealized case: a Schwarzschild black hole of mass M, tidally perturbed by a 'moon' with mass μ >M with orbital angular velocity Ω. We investigate the details of how the tidal deformation of the hole gives rise to an induced quadrupole moment I ij in the hole's external gravitational field at large radii, including the vicinity of the moon. In the limit that the moon is static, we find, in Schwarzschild coordinates and Regge-Wheeler gauge, the surprising result that there is no induced quadrupole moment. We show that this conclusion is gauge dependent and that the static, induced quadrupole moment for a black hole is inherently ambiguous, and we contrast this with an earlier result of Suen, which gave, in a very different gauge, a nonzero static induced quadrupole moment with a sign opposite to what one would get for a fluid central body. For the orbiting moon and the central Schwarzschild hole, we find (in agreement with a recent result of Poisson) a time-varying induced quadrupole moment that is proportional to the time derivative of the moon's tidal field, I ij =(32/45)M 6 E ij and that therefore is out of phase with the tidal field by a spatial angle π/4 and by a temporal phase shift π/2. This induced quadrupole moment produces a gravitational force on the moon that reduces its orbital energy and angular momentum at the same rate as the moon's tidal field sends energy and angular momentum into the hole's horizon. As a partial analog of a result derived long ago by Hartle for a spinning hole and

  19. Evaluation of a Model for Predicting the Tidal Velocity in Fjord Entrances

    Energy Technology Data Exchange (ETDEWEB)

    Lalander, Emilia [The Swedish Centre for Renewable Electric Energy Conversion, Division of Electricity, Uppsala Univ. (Sweden); Thomassen, Paul [Team Ashes, Trondheim (Norway); Leijon, Mats [The Swedish Centre for Renewable Electric Energy Conversion, Division of Electricity, Uppsala Univ. (Sweden)

    2013-04-15

    Sufficiently accurate and low-cost estimation of tidal velocities is of importance when evaluating a potential site for a tidal energy farm. Here we suggest and evaluate a model to calculate the tidal velocity in fjord entrances. The model is compared with tidal velocities from Acoustic Doppler Current Profiler (ADCP) measurements in the tidal channel Skarpsundet in Norway. The calculated velocity value from the model corresponded well with the measured cross-sectional average velocity, but was shown to underestimate the velocity in the centre of the channel. The effect of this was quantified by calculating the kinetic energy of the flow for a 14-day period. A numerical simulation using TELEMAC-2D was performed and validated with ADCP measurements. Velocity data from the simulation was used as input for calculating the kinetic energy at various locations in the channel. It was concluded that the model presented here is not accurate enough for assessing the tidal energy resource. However, the simplicity of the model was considered promising in the use of finding sites where further analyses can be made.

  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. Tidal interactions with Kerr black holes

    International Nuclear Information System (INIS)

    Hiscock, W.A.

    1977-01-01

    The tidal deformation of an extended test body falling with zero angular momentum into a Kerr black hole is calculated. Numerical results for infall along the symmetry axis and in the equatorial plane of the black hole are presented for a range of values of a, the specific angular momentum of the black hole. Estimates of the tidal contribution to the gravitational radiation are also given. The tidal contribution in equatorial infall into a maximally rotating Kerr black hole may be of the same order as the center-of-mass contribution to the gravitational radiation

  2. The effects of low tidal ventilation on lung strain correlate with respiratory system compliance.

    Science.gov (United States)

    Xie, Jianfeng; Jin, Fang; Pan, Chun; Liu, Songqiao; Liu, Ling; Xu, Jingyuan; Yang, Yi; Qiu, Haibo

    2017-02-03

    The effect of alterations in tidal volume on mortality of acute respiratory distress syndrome (ARDS) is determined by respiratory system compliance. We aimed to investigate the effects of different tidal volumes on lung strain in ARDS patients who had various levels of respiratory system compliance. Nineteen patients were divided into high (C high group) and low (C low group) respiratory system compliance groups based on their respiratory system compliance values. We defined compliance ≥0.6 ml/(cmH 2 O/kg) as C high and compliance respiratory system compliance. The mean baseline EELV, strain and respiratory system compliance values were 1873 ml, 0.31 and 0.65 ml/(cmH 2 O/kg), respectively; differences in all of these parameters were statistically significant between the two groups. For all participants, a positive correlation was found between the respiratory system compliance and EELV (R = 0.488, p = 0.034). Driving pressure and strain increased together as the tidal volume increased from 6 ml/kg predicted body weight (PBW) to 12 ml/kg PBW. Compared to the C high ARDS patients, the driving pressure was significantly higher in the C low patients at each tidal volume. Similar effects of lung strain were found for tidal volumes of 6 and 8 ml/kg PBW. The "lung injury" limits for driving pressure and lung strain were much easier to exceed with increases in the tidal volume in C low patients. Respiratory system compliance affected the relationships between tidal volume and driving pressure and lung strain in ARDS patients. These results showed that increasing tidal volume induced lung injury more easily in patients with low respiratory system compliance. Clinicaltrials.gov identifier NCT01864668 , Registered 21 May 2013.

  3. A Simulation Atlas of Tidal Features in Galaxies

    Science.gov (United States)

    Howard, Sethanne; Keel, William C.; Byrd, Gene; Burkey, Jordan

    1993-01-01

    Detailed simulations of tidally induced structure in disk galaxies have either concentrated on specific systems or consisted of a few encounters with relatively small numbers of particles and no self-gravity. Observers need a 'dictionary' of simulations that covers many encounter parameters with fine morphological resolution and includes effects of self-gravitation. Observers can then search the dictionary for the parameters that best match a particular observed morphology. Alternatively, the dictionary can be used with observational samples for statistical studies of system parameters. To fill this need, we present a survey of model tidal encounters using a self-gravitating, 180,000 particle, two-component ('stars' and 'gas') disk. A wide variety of fascinating morphologies results. There are 86 different encounters that vary orbit tilt, perigalacticon distance, galaxy to companion mass ratio, and the amount of halo dark matter relative to the disk. For morphological comparisons, over 1700 images of the entire survey are available in video form. While there is a rich variety of tidal structure covering much of this parameter space, some general patterns may be remarked. There is a strong orbital inclination dependence of the symmetry of tidal patterns, most symmetric for planar orbits and nearly one-sided for polar encounters. Retrograde encounters produce only broad fanlike global patterns, but rich small-scale internal structure. In both kinds of encounter, our numerical resolution allows us to track internal spiral structure driven by the outer material arms, especially in the lighter halo simulations. We note also that polar encounters generate series of expanding, essentially non-rotating loops resembling shell structures in some respects.

  4. Exploitation of tidal power in the Bay of Cadiz: ancient tidal mills

    Directory of Open Access Journals (Sweden)

    José J. Alonso del Rosario

    2006-03-01

    Full Text Available Tidal mills were the main industrial activity in the Bay of Cadiz for centuries. They were the last step in the production of salt and flour made by grinding grains. They were installed along the shallow channels, called “caños”, around the Bay, where the frictional and geometrical effects are very strong. The authors have analyzed the propagation of the semidiurnal tidal waves along the Caño de Sancti Petri and the available tidal power in the area. The ancient tidal mills were located where the available tidal potential energy is highest, which ensured productivity for grinding salt and wheat in ancient times. Some considerations about the possibility of installing tidal power plants in the Bay of Cadiz now are given, which show that it could be a real and renewal alternative source of energy for the area.

  5. Development of tidal watersheds in the Wadden Sea

    NARCIS (Netherlands)

    Wang, Z.B.; Vroom, J.; van Prooijen, B.C.; Labeur, R.J.; Stive, M.J.F.; Hansen, M.H.P.

    2011-01-01

    The Wadden Sea consists of a series of tidal lagoons which are connected to the North Sea by tidal inlets. Boundaries to each lagoon are the mainland coast, the barrier islands on both sides of the tidal inlet, and the tidal watersheds behind the two barrier islands. Behind each Wadden Island there

  6. 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

  7. Tidal Mixing at the Shelf Break

    National Research Council Canada - National Science Library

    Hogg, Nelson; Legg, Sonya

    2005-01-01

    The aim of this project was to study mixing forced by tidal flow over sudden changes in topographic slope such as near the shelf-break, using high-resolution nonhydrostatic numerical simulations employing the MIT gem...

  8. Tides and tidal harmonics at Umbharat, Gujarat

    Digital Repository Service at National Institute of Oceanography (India)

    Suryanarayana, A.; Swamy, G.N.

    A part of the data on tides recorded at Machiwada near Umbharat, Gulf of Cambay during April 1978 was subjected to harmonic analysis following the Admiralty procedure. The general tidal characteristics and the value of four major harmonic...

  9. Tidal mixing in Dahej creek waters

    Digital Repository Service at National Institute of Oceanography (India)

    Swamy, G.N.; Sarma, R.V.

    of effluent discharge has been worked out. The allowable duration of discharge of the hypothetical effluent over a tidal cycle ensuring a specified minimum dilution has also been indicated to help optimise the degree of inplant treatment. The results suggested...

  10. Microbial quality of a marine tidal pool

    CSIR Research Space (South Africa)

    Genthe, Bettina

    1995-01-01

    Full Text Available In this study the source of microbial pollution to a tidal pool was investigated. Both adjacent seawater which could contribute to possible faecal pollution and potential direct bather pollution were studied. The microbial quality of the marine...

  11. 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.

  12. On the ambiguity in relativistic tidal deformability

    Science.gov (United States)

    Gralla, Samuel E.

    2018-04-01

    The LIGO collaboration recently reported the first gravitational-wave constraints on the tidal deformability of neutron stars. I discuss an inherent ambiguity in the notion of relativistic tidal deformability that, while too small to affect the present measurement, may become important in the future. I propose a new way to understand the ambiguity and discuss future prospects for reliably linking observed gravitational waveforms to compact object microphysics.

  13. The environmental effects of tidal energy

    International Nuclear Information System (INIS)

    Muirhead, H.J.

    1992-01-01

    The aim of this paper is to outline the environmental effects of tidal energy in relation to the estuarine ecosystem, and therefore will not deal with the regional environmental and socioeconomic implications of tidal power. The topics covered are: hydrodynamics of sediments; turbidity; water quality; fish; birds and wildlife conservation. The nature of the estuarine environment and how, as a system, it works, is briefly described by way of introduction. (author)

  14. Pond fractals in a tidal flat

    OpenAIRE

    Cael, B. B.; Bisson, Kelsey; Lambert, Bennett Spencer

    2015-01-01

    Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during low tide of a tidal flat in Damariscotta, Maine, reveal a well-resolved power-law distribution of p...

  15. WIYN Open Cluster Study: Tidal Interactions in Solar type Binaries

    OpenAIRE

    Meibom, S.; Mathieu, R. D.

    2003-01-01

    We present an ongoing study on tidal interactions in late-type close binary stars. New results on tidal circularization are combined with existing data to test and constrain theoretical predictions of tidal circularization in the pre-main-sequence (PMS) phase and throughout the main-sequence phase of stellar evolution. Current data suggest that tidal circularization during the PMS phase sets the tidal cutoff period for binary populations younger than ~1 Gyr. Binary populations older than ~1 G...

  16. Ocean renewable energy : Tidal power in the Yellow Sea

    OpenAIRE

    Lee, Han Soo

    2011-01-01

    Ocean renewable energy sources are briefly introduced in this review article. Special focus on tidal energy from ocean renewable energy in the Yellow Sea and its practical utilization in South Korea are illustrated with several examples. Among them, the Sihwa Lake tidal power plant, the Garolim Bay tidal power project, the Incheon tidal power project, and the Uldolmok tidal current power station were introduced with more details. A numerical modelling system, Regional Ocean Tide Simulator, is...

  17. TIDAL INTERACTIONS IN MERGING WHITE DWARF BINARIES

    International Nuclear Information System (INIS)

    Piro, Anthony L.

    2011-01-01

    The recently discovered system J0651 is the tightest known detached white dwarf (WD) binary. Since it has not yet initiated Roche-lobe overflow, it provides a relatively clean environment for testing our understanding of tidal interactions. I investigate the tidal heating of each WD, parameterized in terms of its tidal Q parameter. Assuming that the heating can be radiated efficiently, the current luminosities are consistent with Q 1 ∼ 7 x 10 10 and Q 2 ∼ 2 x 10 7 , for the He and C/O WDs, respectively. Conversely, if the observed luminosities are merely from the cooling of the WDs, these estimated values of Q represent the upper limits. A large Q 1 for the He WD means its spin velocity will be slower than that expected if it was tidally locked, which, since the binary is eclipsing, may be measurable via the Rossiter-McLaughlin effect. After one year, gravitational wave emission shifts the time of eclipses by 5.5 s, but tidal interactions cause the orbit to shrink more rapidly, changing the time by up to an additional 0.3 s after a year. Future eclipse timing measurements may therefore infer the degree of tidal locking.

  18. VISCOELASTIC MODELS OF TIDALLY HEATED EXOMOONS

    International Nuclear Information System (INIS)

    Dobos, Vera; Turner, Edwin L.

    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 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

  19. 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.

  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. Critical width of tidal flats triggers marsh collapse in the absence of sea-level rise.

    Science.gov (United States)

    Mariotti, Giulio; Fagherazzi, Sergio

    2013-04-02

    High rates of wave-induced erosion along salt marsh boundaries challenge the idea that marsh survival is dictated by the competition between vertical sediment accretion and relative sea-level rise. Because waves pounding marshes are often locally generated in enclosed basins, the depth and width of surrounding tidal flats have a pivoting control on marsh erosion. Here, we show the existence of a threshold width for tidal flats bordering salt marshes. Once this threshold is exceeded, irreversible marsh erosion takes place even in the absence of sea-level rise. This catastrophic collapse occurs because of the positive feedbacks among tidal flat widening by wave-induced marsh erosion, tidal flat deepening driven by wave bed shear stress, and local wind wave generation. The threshold width is determined by analyzing the 50-y evolution of 54 marsh basins along the US Atlantic Coast. The presence of a critical basin width is predicted by a dynamic model that accounts for both horizontal marsh migration and vertical adjustment of marshes and tidal flats. Variability in sediment supply, rather than in relative sea-level rise or wind regime, explains the different critical width, and hence erosion vulnerability, found at different sites. We conclude that sediment starvation of coastlines produced by river dredging and damming is a major anthropogenic driver of marsh loss at the study sites and generates effects at least comparable to the accelerating sea-level rise due to global warming.

  2. 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...

  3. Analysing monthly sectorial water use and its influence on salt intrusion induced water shortage in urbanized deltas

    NARCIS (Netherlands)

    Yao, Mingtian; Yan, Dan; Kabat, Pavel; Huang, Heqing; Hutjes, Ronald W.A.; Werners, Saskia E.

    2016-01-01

    Urbanizing delta regions face seasonal water shortages induced by rising salt intrusion. Decreasing river discharge is readily listed as the major cause of water shortage events. Yet, observations of river discharge often fail to support this attribution. Evidence of the association between

  4. Histological and Biochemical Analyses of the Effects of Royal Jelly and Vitamin C against Phenylhydrazine-Induced Cardiotoxicity in Mice

    Directory of Open Access Journals (Sweden)

    Hojat Anbara

    2017-10-01

    Full Text Available Abstract Background: Phenylhydrazine (PHZ as a strong oxidant agent causes variety of toxic effects including alterations in the biochemical and cardiac tissue. The aim of the present study was to investigate the effects of royal jelly (RJ and vitamin C (vit C against PHZ-induced cardiotoxicity in mice. Materials and Methods: Adult male mice were randomly assigned to eight groups of eight mice each. PHZ was administered to four groups of mice at a dose of 60 mg/kg per 48 hours intraperitoneally for 35 days. Three of these groups received vit C (250 mg/kg per day intraperitoneally, RJ (100 mg/kg per day orally and vit C+RJ with same doses four hours before PHZ administration, respectively. A vehicle-treated control group and vit C, RJ and vit C+RJ control groups were also included. Results: RJ and vit C significantly decreased (p< 0.05 the serum level of malondialdehyde and creatine kinase (CK-BM that had been increased by PHZ. Also, RJ and vit C increased the total antioxidant capacity and supraxoid dismutase serum that had been decreased by induced PHZ. Moreover, RJ and vit C could improve the tissue damages induced by PHZ such as diffused edema, hemorrhage, congestion, hyaline exudates, necrosis and also fibrosis tissue in heart tissue. Conclusion: It seems that Vit C and RJ can minimize PHZ-induced cardiotoxicity in mouse through oxidative reactions inhibition.

  5. Viscoelasticity of articular cartilage: Analysing the effect of induced stress and the restraint of bone in a dynamic environment.

    Science.gov (United States)

    Lawless, Bernard M; Sadeghi, Hamid; Temple, Duncan K; Dhaliwal, Hemeth; Espino, Daniel M; Hukins, David W L

    2017-11-01

    The aim of this study was to determine the effect of the induced stress and restraint provided by the underlying bone on the frequency-dependent storage and loss stiffness (for bone restraint) or modulus (for induced stress) of articular cartilage, which characterise its viscoelasticity. Dynamic mechanical analysis has been used to determine the frequency-dependent viscoelastic properties of bovine femoral and humeral head articular cartilage. A sinusoidal load was applied to the specimens and out-of-phase displacement response was measured to determine the phase angle, the storage and loss stiffness or modulus. As induced stress increased, the storage modulus significantly increased (p 0.05); however, off-bone, articular cartilage loss stiffness demonstrated a logarithmic frequency-dependency (p < 0.05). In conclusion, the frequency-dependent trends of storage and loss moduli of articular cartilage are dependent on the induced stress, while the restraint provided by the underlying bone removes the frequency-dependency of the loss stiffness. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  6. Transcriptome analyses and virus induced gene silencing identify genes in the Rpp4-mediated Asian soybean rust resistance pathway

    Science.gov (United States)

    Rpp4 (Resistance to Phakopsora pachyrhizi 4) confers resistance to P. pachyrhizi, the causal agent of Asian soybean rust (ASR). By combining expression profiling and virus induced gene silencing (VIGS), we are developing a genetic framework for Rpp4-mediated resistance. We measured gene expression i...

  7. 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)

  8. 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

  9. 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

  10. Tidal exchange between a freshwater tidal marsh and an impacted estuary: the Scheldt estuary, Belgium

    NARCIS (Netherlands)

    van Damme, S.; Dehairs, F.; Tackx, M.; Beauchard, O.; Struyf, E.; Gribsholt, B.; van Cleemput, O.; Meire, P.

    2009-01-01

    Tidal marsh exchange studies are relatively simple tools to investigate the interaction between tidal marshes and estuaries. They have mostly been confined to only a few elements and to saltwater or brackish systems. This study presents mass-balance results of an integrated one year campaign in a

  11. A comparative study of nitrogen and phosphorus cycling in tidal and non-tidal riverine wetlands

    NARCIS (Netherlands)

    Verhoeven, J. T.A.; Whigham, D.F.; van Logtestijn, R.; O'Neill, J.K.

    2001-01-01

    This paper describes a study of nutrient dynamics in 12 tidal and non-tidal freshwater riverine wetlands in The Netherlands, Belgium, and Maryland (USA). The purpose of the study was to investigate the relationships between nutrient cycling processes in riverine wetlands that were geographically

  12. Bio-geomorphic effects on tidal channel evolution: impact of vegetation establishment and tidal prism change

    NARCIS (Netherlands)

    Vandenbruwaene, W.; Meire, P.; Temmerman, S.; Bouma, T.J.

    2013-01-01

    The long-term (10–100 years) evolution of tidal channels is generally considered to interact with the bio-geomorphic evolution of the surrounding intertidal platform. Here we studied how the geometric properties of tidal channels (channel drainage density and channel width) change as (1) vegetation

  13. Biochemical and proteomic analyses of the physiological response induced by individual housing in gilts provide new potential stress markers

    OpenAIRE

    Marco Ramell, Anna; Arroyo, Laura; Peña, Raquel; Pato, Raquel; Saco, Yolanda; Fraile Sauce, Lorenzo José; Bendixen, Emøke; Bassols, Anna

    2016-01-01

    Background The objective assessment of animal stress and welfare requires proper laboratory biomarkers. In this work, we have analyzed the changes in serum composition in gilts after switching their housing, from pen to individual stalls, which is generally accepted to cause animal discomfort. Results Blood and saliva samples were collected a day before and up to four days after changing the housing system. Biochemical analyses showed adaptive changes in lipid and protein metabolism after the...

  14. Tidal breathing flow measurement in awake young children by using impedance pneumography.

    Science.gov (United States)

    Seppä, Ville-Pekka; Pelkonen, Anna S; Kotaniemi-Syrjänen, Anne; Mäkelä, Mika J; Viik, Jari; Malmberg, L Pekka

    2013-12-01

    Characteristics of tidal breathing (TB) relate to lung function and may be assessed even in young children. Thus far, the accuracy of impedance pneumography (IP) in recording TB flows in young children with or without bronchial obstruction has not been evaluated. The aim of this study was to evaluate the agreement between IP and direct flow measurement with pneumotachograph (PNT) in assessing TB flow and flow-derived indices relating to airway obstruction in young children. Tidal flow was recorded for 1 min simultaneously with IP and PNT during different phases of a bronchial challenge test with methacholine in 21 wheezy children aged 3 to 7 years. The agreement of IP with PNT was found to be excellent in direct flow signal comparison, the mean deviation from linearity ranging from 2.4 to 3.1% of tidal peak inspiratory flow. Methacholine-induced bronchoconstriction or consecutive bronchodilation induced only minor changes in the agreement. Between IP and PNT, the obstruction-related tidal flow indices were equally repeatable, and agreement was found to be high, with intraclass correlation coefficients for T PTEF/T E, V PTEF/V E, and parameter S being 0.94, 0.91, and 0.68, respectively. Methacholine-induced changes in tidal flow indices showed significant associations with changes in mechanical impedance of the respiratory system assessed by the oscillometric technique, with the highest correlation found in V PTEF/V E (r = -0.54; P tidal airflow profiles in young children with wheezing disorders.

  15. 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

  16. Effect of Long Term Tidal Constituents on Mean Sea Level Trend during El-Nino and La-Nina Phenomena

    Science.gov (United States)

    Yusof, N. H. M.; Mahmud, M. R.; Abdullah, M. H.

    2017-10-01

    There are many factors that influence the change of the tidal constituent pattern. The factors can be classified as astronomical factors and non- astronomical factors. The astronomical factors involve the gravitational force attraction by the moon and sun. The distance of sun and moon influence the gravitational attractions that are produced by the moon and sun towards earth surface. Non-astronomical factors involved the movements of currents, waves, temperature and so on which is cause by the phenomenon such as El-Nino, La-Nina. This study was conducted to investigate the effect of these phenomena towards the pattern of tidal constituent during the phenomenon on several stations that have been chosen. The difference stations were chose due to the change in the position of celestial body. In addition, tidal data for several stations were processed using the UTM Tidal Analysis and Prediction Software (μ-TAPS). Based on the tidal data that has been processed, the graphs were plotted for the predicted data and observed data to compare the different pattern between the data. The tidal data that has been processed were used to analyse the pattern of tidal constituents based on the changing amplitude of M2, S2, K1, O1, Sa, Ssa, Mm, Mf and MSf.

  17. 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

    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...... that in some coastal regions the amplitudes of the electric field can reach 100 mV/km and 10 mV/km for M2 and O1 tides respectively. The changes of lithosphere resistance produce detectable changes in the tidal electric signals. We show that our predictions are in a good agreement with observations....

  18. Tidal volume and mortality in mechanically ventilated children: a systematic review and meta-analysis of observational studies*.

    Science.gov (United States)

    de Jager, Pauline; Burgerhof, Johannes G M; van Heerde, Marc; Albers, Marcel J I J; Markhorst, Dick G; Kneyber, Martin C J

    2014-12-01

    To determine whether tidal volume is associated with mortality in critically ill, mechanically ventilated children. MEDLINE, EMBASE, and CINAHL databases from inception until July 2013 and bibliographies of included studies without language restrictions. Randomized clinical trials and observational studies reporting mortality in mechanically ventilated PICU patients. Two authors independently selected studies and extracted data on study methodology, quality, and patient outcomes. Meta-analyses were performed using the Mantel-Haenszel random-effects model. Heterogeneity was quantified using I. Study quality was assessed using the Newcastle-Ottawa Score for cohort studies. Out of 142 citations, seven studies met the inclusion criteria, and additional two articles were identified from references of the found articles. One was excluded. These eight studies included 1,756 patients. Mortality rates ranged from 13% to 42%. There was no association between tidal volume and mortality when tidal volume was dichotomized at 7, 8, 10, or 12 mL/kg. Comparing patients ventilated with tidal volume less than 7 mL/kg and greater than 10 mL/kg or greater than 12 mL/kg and tidal volume less than 8 mL/kg and greater than 10 mL/kg or greater than 12 mL/kg also showed no association between tidal volume and mortality. Limiting the analysis to patients with acute lung injury/acute respiratory distress syndrome did not change these results. Heterogeneity was observed in all pooled analyses. A relationship between tidal volume and mortality in mechanically ventilated children could not be identified, irrespective of the severity of disease. The significant heterogeneity observed in the pooled analyses necessitates future studies in well-defined patient populations to understand the effects of tidal volume on patient outcome.

  19. On the migration rate of tidal meanders

    Science.gov (United States)

    D'Alpaos, A.; Finotello, A.; Ghinassi, M.; Lanzoni, S.; Marani, M.; Rinaldo, A.

    2016-12-01

    Sinuous channels shaped by periodically reversing tidal flows are a ubiquitous feature of tidal landscapes. Despite their fundamental role on the morphology and sedimentary patterns of these landscapes, tidal meanders have received less attention than their fluvial counterparts, particularly as far as migration processes are concerned. We have analyzed the migration of about 300 meander bends in the Northern Venice Lagoon (Italy), from 1968 to nowadays, through observations and modeling interpretation. Similarities with fluvial meanders occur, although important difference also emerge. Meanders cutting through salt-marshes in the Venice Lagoon follow the relationship between Cartesian length and channel width, typical of meanders developed within different settings. We find a mean migration rate of about 0.20 m/year. However, the potential migration rate can reach values of about 0.20 channel widths per year thus suggesting similarities with fluvial meanders. In addition, tidal channel migration dynamics displays features which qualitatively agree with theories developed for the fluvial setting. We deem our results are valuable for the understanding of the morphological evolution and architecture of tidal landscapes, with implications for restoration strategies, also in the face of changes in environmental conditions.

  20. 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.

  1. Ridges and tidal stress on Io

    Science.gov (United States)

    Bart, G.D.; Turtle, E.P.; Jaeger, W.L.; Keszthelyi, L.P.; Greenberg, R.

    2004-01-01

    Sets of ridges of uncertain origin are seen in twenty-nine high-resolution Galileo images, which sample seven locales on Io. These ridges are on the order of a few kilometers in length with a spacing of about a kilometer. Within each locale, the ridges have a consistent orientation, but the orientations vary from place to place. We investigate whether these ridges could be a result of tidal flexing of Io by comparing their orientations with the peak tidal stress orientations at the same locations. We find that ridges grouped near the equator are aligned either north-south or east-west, as are the predicted principal stress orientations there. It is not clear why particular groups run north-south and others east-west. The one set of ridges observed far from the equator (52?? S) has an oblique azimuth, as do the tidal stresses at those latitudes. Therefore, all observed ridges have similar orientations to the tidal stress in their region. This correlation is consistent with the hypothesis that tidal flexing of Io plays an important role in ridge formation. ?? 2004 Elsevier Inc. All rights reserved.

  2. Whole-transcriptome analyses of the Sapsaree, a Korean natural monument, before and after exercise-induced stress

    Directory of Open Access Journals (Sweden)

    Ji-Eun Kim

    2016-04-01

    Full Text Available Abstract Background The Sapsaree (Canis familiaris is a Korean native dog that is very friendly, protective, and loyal to its owner, and is registered as a natural monument in Korea (number: 368. To investigate large-scale gene expression profiles and identify the genes related to exercise-induced stress in the Sapsaree, we performed whole-transcriptome RNA sequencing and analyzed gene expression patterns before and after exercise performance. Results We identified 525 differentially expressed genes in ten dogs before and after exercise. Gene Ontology classification and KEGG pathway analysis revealed that the genes were mainly involved in metabolic processes, such as programmed cell death, protein metabolic process, phosphatidylinositol signaling system, and cation binding in cytoplasm. The ten Sapsarees could be divided into two groups based on the gene expression patterns before and after exercise. The two groups were significantly different in terms of their basic body type (p ≤ 0.05. Seven representative genes with significantly different expression patterns before and after exercise between the two groups were chosen and characterized. Conclusions Body type had a significant effect on the patterns of differential gene expression induced by exercise. Whole-transcriptome sequencing is a useful method for investigating the biological characteristics of the Sapsaree and the large-scale genomic differences of canines in general.

  3. Protective Effect of Royal Jelly against Phenylhydrazine-induced Histological Injuries of Small Intestine of Mice: Morphometric Analyses

    Directory of Open Access Journals (Sweden)

    Hojat Anbara

    2016-01-01

    Full Text Available Background and Objectives: Phenylhydrazine (PHZ, as a known hemolytic agent, causes toxicity in different tissues at various levels. The aim of the current study was to examine the possible protective effects of royal jelly (RJ against PHZ-induced histological injuries of small intestine in mice.   Methods: In this experimental study, adult male mice were randomly divided into four groups of 8 mice each. PHZ was administered intraperitoneally to two groups of mice (at a dose of 60mg/kg every 48 hours for 35 days. One of the groups received RJ (100mg/kg orally 4 hours before PHZ administration. The third group only received RJ, and the forth group was considered as control. Twenty-four hours after the last treatment, different segments of small intestine were dissected out, then histological sections were prepared and quantitative morphometric assessments were performed. To compare the groups, one-way ANOVA and multiple comparative Tukey tests were used. The significance level was considered to be p<0.05.   Results: In this study, PHZ caused significant decreases in depth of duodenal crypts, distribution rate of the goblet cells in ileal villi, width of duodenal and jejunal villi, and height of villi in all three segments of small intestine. Co-administration of RJ partially improved the changes in the above parameters.   Conclusion: From results of this study, it seems that RJ as a free radical scavenger could reduce PHZ-induced intestinal toxicity in mouse.

  4. Tidal Control of Jet Eruptions on Enceladus as Observed by Cassini ISS between 2005 and 2007

    Science.gov (United States)

    Hurford, T. A.; Helfenstein, P.; Spitale, J. N.

    2012-01-01

    Observations of Enceladus have revealed active jets of material erupting from cracks on its south polar surface. It has previously been proposed that diurnal tidal stress, driven by Enceladus' orbital eccentricity, may actively produce surface movement along these cracks daily and thus may regulate when eruptions occur. Our analysis of the stress on jet source regions identified in Cassini ISS images reveals tidal stress as a plausible controlling mechanism of jet activity. However, the evidence available in the published and preliminary observations of jet activity between 2005 and 2007 may not be able to solidify the link between tidal stress and eruptions from fissures. Ongoing, far more comprehensive analyses based on recent, much higher resolution jetting observations have the potential to prove otherwise.

  5. The joint probability method of determining the flood return period of a tidally affected pond

    Energy Technology Data Exchange (ETDEWEB)

    Gorji-Bandpy, M. [Mazandaran Univ. (Iran). School of Engineering

    2001-07-01

    In this paper a method is presented for determining the return period of flood levels within detention ponds used to store surface water runoff for affected coastal catchments. A simulation method is proposed in probability space based on deriving the joint probability of occurrence of pond levels by combining the probability of the rainfall inflow hydrograph and peak tidal amplitudes. Each combination of events is then analysed and the overall pond level statistics of the site produced. The results are to be used in an attempt to produce a rational approach to the problem of the design of detention ponds in coastal regions. The technique was applied to an existing tidally affected pond that is surcharged at the outlet due to occurrence of tidal fluctuations. The results prove that the traditional design assumptions that the peak inflow occurs at the peak high tide is pessimistic and leads to overdesigned systems. (orig.)

  6. Enhanced winds and tidal streams in massive X-ray binaries

    International Nuclear Information System (INIS)

    Blondin, J.M.; Stevens, I.R.; Kallman, T.R.

    1991-01-01

    The tidal effects created by the presence of a compact companion are expected to induce a stream of enhanced wind from the early-type primary star in massive X-ray binary systems. In this paper, two-dimensional gasdynamical simulations of such streams are presented. It is found that the wind enhancement is a sensitive function of the binary separation, and develops into a tidal stream as the primary approaches its critical surface. For typical system parameters, the Coriolis force deflects the stream sufficiently that it does not impact directly on the compact companion but passes behind it. The density in the stream can reach values of 20-30 times the ambient wind density, leading to strong attenuation of the X-ray flux that passes through the tidal stream, providing a possible explanation of the enhanced absorption events seen at later phases in the X-ray observations of massive X-ray binary systems such as Vela X-1. In contrast to the time-variable accretion wake, the tidal stream is relatively stationary, producing absorption features that should remain fixed from orbit to orbit. For systems with a strong tidal stream, the large asymmetry in the accreting wind results in the accretion of angular momentum of constant sign, as opposed to systems without streams, where the sign of the accreted angular momentum can change. 39 refs

  7. Integration of Tidal Prism Model and HSPF for simulating indicator bacteria in coastal watersheds

    Science.gov (United States)

    Sobel, Rose S.; Rifai, Hanadi S.; Petersen, Christina M.

    2017-09-01

    Coastal water quality is strongly influenced by tidal fluctuations and water chemistry. There is a need for rigorous models that are not computationally or economically prohibitive, but still allow simulation of the hydrodynamics and bacteria sources for coastal, tidally influenced streams and bayous. This paper presents a modeling approach that links a Tidal Prism Model (TPM) implemented in an Excel-based modeling environment with a watershed runoff model (Hydrologic Simulation Program FORTRAN, HSPF) for such watersheds. The TPM is a one-dimensional mass balance approach that accounts for loading from tidal exchange, runoff, point sources and bacteria die-off at an hourly time step resolution. The novel use of equal high-resolution time steps in this study allowed seamless integration of the TPM and HSPF. The linked model was calibrated to flow and E. Coli data (for HSPF), and salinity and enterococci data (for the TPM) for a coastal stream in Texas. Sensitivity analyses showed the TPM to be most influenced by changes in net decay rates followed by tidal and runoff loads, respectively. Management scenarios were evaluated with the developed linked models to assess the impact of runoff load reductions and improved wastewater treatment plant quality and to determine the areas of critical need for such reductions. Achieving water quality standards for bacteria required load reductions that ranged from zero to 90% for the modeled coastal stream.

  8. Analyses and computer code developments for accident-induced thermohydraulic transients in water-cooled nuclear reactor systems

    International Nuclear Information System (INIS)

    Wulff, W.

    1977-01-01

    A review is presented on the development of analyses and computer codes for the prediction of thermohydraulic transients in nuclear reactor systems. Models for the dynamics of two-phase mixtures are summarized. Principles of process, reactor component and reactor system modeling are presented, as well as the verification of these models by comparing predicted results with experimental data. Codes of major importance are described, which have recently been developed or are presently under development. The characteristics of these codes are presented in terms of governing equations, solution techniques and code structure. Current efforts and problems of code verification are discussed. A summary is presented of advances which are necessary for reducing the conservatism currently implied in reactor hydraulics codes for safety assessment

  9. 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.

  10. Tidal analysis of Met rocket wind data

    Science.gov (United States)

    Bedinger, J. F.; Constantinides, E.

    1976-01-01

    A method of analyzing Met Rocket wind data is described. Modern tidal theory and specialized analytical techniques were used to resolve specific tidal modes and prevailing components in observed wind data. A representation of the wind which is continuous in both space and time was formulated. Such a representation allows direct comparison with theory, allows the derivation of other quantities such as temperature and pressure which in turn may be compared with observed values, and allows the formation of a wind model which extends over a broader range of space and time. Significant diurnal tidal modes with wavelengths of 10 and 7 km were present in the data and were resolved by the analytical technique.

  11. TIDAL TURBULENCE SPECTRA FROM A COMPLIANT MOORING

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, Jim; Kilcher, Levi; Richmond, Marshall C.; Talbert, Joe; deKlerk, Alex; Polagye, Brian; Guerra, Maricarmen; Cienfuegos, Rodrigo

    2013-06-13

    A compliant mooring to collect high frequency turbulence data at a tidal energy site is evaluated in a series of short demon- stration deployments. The Tidal Turbulence Mooring (TTM) improves upon recent bottom-mounted approaches by suspend- ing Acoustic Doppler Velocimeters (ADVs) at mid-water depths (which are more relevant to tidal turbines). The ADV turbulence data are superior to Acoustic Doppler Current Profiler (ADCP) data, but are subject to motion contamination when suspended on a mooring in strong currents. In this demonstration, passive stabilization is shown to be sufficient for acquiring bulk statistics of the turbulence, without motion correction. With motion cor- rection (post-processing), data quality is further improved; the relative merits of direct and spectral motion correction are dis- cussed.

  12. Increased Tidal Dissipation Using Advanced Rheological Models: Implications for Io and Tidally Active Exoplanets

    Science.gov (United States)

    Renaud, Joe P.; Henning, Wade G.

    2018-04-01

    The advanced rheological models of Andrade and Sundberg & Cooper are compared to the traditional Maxwell model to understand how each affects the tidal dissipation of heat within rocky bodies. We find both Andrade and Sundberg–Cooper rheologies can produce at least 10× the tidal heating compared to a traditional Maxwell model for a warm (1400–1600 K) Io-like satellite. Sundberg–Cooper can cause even larger dissipation around a critical temperature and frequency. These models allow cooler planets to stay tidally active in the face of orbital perturbations—a condition we term “tidal resilience.” This has implications for the time evolution of tidally active worlds and the long-term equilibria they fall into. For instance, if Io’s interior is better modeled by the Andrade or Sundberg–Cooper rheologies, the number of possible resonance-forming scenarios that still produce a hot, modern Io is expanded, and these scenarios do not require an early formation of the Laplace resonance. The two primary empirical parameters that define the Andrade anelasticity are examined in several phase spaces to provide guidance on how their uncertainties impact tidal outcomes, as laboratory studies continue to constrain their real values. We provide detailed reference tables on the fully general equations required for others to insert the models of Andrade and Sundberg–Cooper into standard tidal formulae. Lastly, we show that advanced rheologies can greatly impact the heating of short-period exoplanets and exomoons, while the properties of tidal resilience could mean a greater number of tidally active worlds among all extrasolar systems.

  13. 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.

  14. Short period tidal variations of earth rotation

    Science.gov (United States)

    Yoder, C. F.; Williams, J. G.; Parke, M. E.; Dickey, J. O.

    1981-01-01

    It is explained that the tidal deformation of the earth's polar moment of inertia by the moon and sun cause periodic variations in rotation. The short period oscillations give rise to a meter-sized, diurnal signature in the lunar laser ranging data obtained at McDonald Observatory. A solution is given for the scale parameter k/C at fortnightly and monthly tidal frequencies. The results are compared with those obtained by other investigators and with a theoretical estimate which includes the effect of oceans and a decoupled fluid core.

  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. Analyses of variant human papillomavirus type-16 E5 proteins for their ability to induce mitogenesis of murine fibroblasts

    Directory of Open Access Journals (Sweden)

    Cason John

    2006-08-01

    Full Text Available Abstract Background Human papillomavirus type 16 (HPV-16 E5 protein co-operates with epidermal growth factor to stimulate mitogenesis of murine fibroblasts. Currently, little is known about which viral amino acids are involved in this process. Using sequence variants of HPV-16 E5 we have investigated their effects upon E5 transcription, cell-cycling and cell-growth of murine fibroblasts. Results We demonstrate that: (i introduction of Thr64 into the reference E5 sequence of HPV-16 abrogates mitogenic activity: both were poorly transcribed in NIH-3T3 cells; (ii substitution of Leu44Val65 or, Thr37Leu44Val65 into the HPV-16 E5 reference backbone resulted in high transcription in NIH-3T3 cells, enhanced cell-cycle progression and high cell-growth; and, (iii inclusion of Tyr8 into the Leu44Val65 backbone inhibited E5 induced cell-growth and repression of p21 expression, despite high transcription levels. Conclusion The effects of HPV-16 E5 variants upon mitosis help to explain why Leu44Val65 HPV-16 E5 variants are most prevalent in 'wild' pathogenic viral populations in the UK.

  17. Recognition of Earthquake-Induced Damage in the Abakainon Necropolis (NE Sicily): Results From Geomorphological, Geophysical and Numerical Analyses

    Science.gov (United States)

    Bottari, C.; Albano, M.; Capizzi, P.; D'Alessandro, A.; Doumaz, F.; Martorana, R.; Moro, M.; Saroli, M.

    2018-01-01

    Seismotectonic activity and slope instability are a permanent threat in the archaeological site of Abakainon and in the nearby village of Tripi in NE Sicily. In recent times, signs of an ancient earthquake have been identified in the necropolis of Abakainon which dating was ascertained to the first century AD earthquake. The site is located on a slope of Peloritani Mts. along the Tindari Fault Line and contains evidence for earthquake-induced landslide, including fallen columns and blocks, horizontal shift and counter slope tilting of the tomb basements. In this paper, we used an integrated geomorphological and geophysical analysis to constrain the landslide. The research was directed to the acquisition of deep geological data for the reconstruction of slope process and the thickness of mobilized materials. The applied geophysical techniques included seismic refraction tomography and electrical resistivity tomography. The surveys were performed to delineate the sliding surface and to assess approximately the thickness of mobilized materials. The geophysical and geomorphologic data confirmed the presence of different overlapped landslides in the studied area. Moreover, a numerical simulation of the slope under seismic loads supports the hypothesis of a mobilization of the landslide mass in case of strong earthquakes (PGA > 0.3 g). However, numerical results highlight that the main cause of destruction for the Abakainon necropolis is the amplification of the seismic waves, occasionally accompanied by surficial sliding.

  18. Comparative Metabolomic Analyses of Ipomoea lacunosa Biotypes with Contrasting Glyphosate Tolerance Captures Herbicide-Induced Differential Perturbations in Cellular Physiology.

    Science.gov (United States)

    Maroli, Amith S; Nandula, Vijay K; Duke, Stephen O; Gerard, Patrick; Tharayil, Nishanth

    2018-02-28

    Glyphosate-tolerant Ipomoea lacunosa is emerging as a problematic weed in the southeastern United States. Metabolomic profiling was conducted to examine the innate physiology and the glyphosate induced perturbations in two biotypes of I. lacunosa (WAS and QUI) that had contrasting glyphosate tolerance. Compared to the less tolerant QUI-biotype, the innate metabolism of the more tolerant WAS-biotype was characterized by a higher abundance of amino acids, and pyruvate; whereas the sugar profile of the QUI biotype was dominated by the transport sugar sucrose. Glyphosate application (80 g ae/ha) caused similar shikimate accumulation in both biotypes. Compared to QUI, in WAS, the content of aromatic amino acids was less affected by glyphosate treatment, and the content of Ala, Val, Ile, and Pro increased. However, the total sugars decreased by ∼75% in WAS, compared to ∼50% decrease in QUI. The innate, higher proportional abundance, of the transport-sugar sucrose in QUI coud partly explain the higher translocation and greater sensitivity of this biotype to glyphosate. The decrease in sugars, accompanied by an increase in amino acids could delay feedback regulation of upstream enzymes of the shikimate acid pathway in WAS, which could contribute to a greater glyphosate tolerance. Our study, through a metabolomics approach, provides complementary data that elucidates the cellular physiology of herbicide tolerance in Ipomoea lacunosa biotypes.

  19. Goldtraces on wedge-shaped artefacts from late neolithic of south Scandinavia analysed by proton induced x-ray emission spectroscopy

    International Nuclear Information System (INIS)

    Ahlberg, M.; Akselsson, R.; Forkman, B.; Rausing, G.

    1975-01-01

    Visible coloured traces on the surface of two selected wedge-shaped artefacts (pendants) of slate from the late Neolithic of South Scandinavia was analysed by means of proton-induced x-ray emission spectroscopy (PIXE). PIXE is shown to be a feasible tool in investigating surface layers of archeological significance. Three different gold-silver alloys was found on the two pendants. The results indicate that we shall have to reconsider the general accepted theories on the economic basis of the early Bronze Age in the area. (author)

  20. 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...

  1. Tidal flow characteristics at Kasheli (Kalwa/ Bassein creek), Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Swamy, G.N.; Suryanarayana, A.

    Tidal flow characteristics of waters at Kasheli, connected to the sea through Thane and Bassein Creeks in Bombay, Maharashtra, India are investigated based on tide and current observations carried out in 1980-81. The results establish that the tidal...

  2. Tidal capture of stars by a massive black hole

    Science.gov (United States)

    Novikov, I. D.; Pethick, C. J.; Polnarev, A. G.

    1992-01-01

    The processes leading to tidal capture of stars by a massive black hole and the consequences of these processes in a dense stellar cluster are discussed in detail. When the amplitude of a tide and the subsequent oscillations are sufficiently large, the energy deposited in a star after periastron passage and formation of a bound orbit cannot be estimated directly using the linear theory of oscillations of a spherical star, but rather numerical estimates must be used. The evolution of a star after tidal capture is discussed. The maximum ratio R of the cross-section for tidal capture to that for tidal disruption is about 3 for real systems. For the case of a stellar system with an empty capture loss cone, even in the case when the impact parameter for tidal capture only slightly exceeds the impact parameter for direct tidal disruption, tidal capture would be much more important than tidal disruption.

  3. The enhanced value of combining conventional and 'omics' analyses in early assessment of drug-induced hepatobiliary injury

    International Nuclear Information System (INIS)

    Ellinger-Ziegelbauer, Heidrun; Adler, Melanie; Amberg, Alexander; Brandenburg, Arnd; Callanan, John J.; Connor, Susan; Fountoulakis, Michael; Gmuender, Hans; Gruhler, Albrecht; Hewitt, Philip; Hodson, Mark; Matheis, Katja A.; McCarthy, Diane; Raschke, Marian; Riefke, Bjoern; Schmitt, Christina S.; Sieber, Max; Sposny, Alexandra; Suter, Laura; Sweatman, Brian

    2011-01-01

    The InnoMed PredTox consortium was formed to evaluate whether conventional preclinical safety assessment can be significantly enhanced by incorporation of molecular profiling ('omics') technologies. In short-term toxicological studies in rats, transcriptomics, proteomics and metabolomics data were collected and analyzed in relation to routine clinical chemistry and histopathology. Four of the sixteen hepato- and/or nephrotoxicants given to rats for 1, 3, or 14 days at two dose levels induced similar histopathological effects. These were characterized by bile duct necrosis and hyperplasia and/or increased bilirubin and cholestasis, in addition to hepatocyte necrosis and regeneration, hepatocyte hypertrophy, and hepatic inflammation. Combined analysis of liver transcriptomics data from these studies revealed common gene expression changes which allowed the development of a potential sequence of events on a mechanistic level in accordance with classical endpoint observations. This included genes implicated in early stress responses, regenerative processes, inflammation with inflammatory cell immigration, fibrotic processes, and cholestasis encompassing deregulation of certain membrane transporters. Furthermore, a preliminary classification analysis using transcriptomics data suggested that prediction of cholestasis may be possible based on gene expression changes seen at earlier time-points. Targeted bile acid analysis, based on LC-MS metabonomics data demonstrating increased levels of conjugated or unconjugated bile acids in response to individual compounds, did not provide earlier detection of toxicity as compared to conventional parameters, but may allow distinction of different types of hepatobiliary toxicity. Overall, liver transcriptomics data delivered mechanistic and molecular details in addition to the classical endpoint observations which were further enhanced by targeted bile acid analysis using LC/MS metabonomics.

  4. 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.

  5. Biochemical and proteomic analyses of the physiological response induced by individual housing in gilts provide new potential stress markers.

    Science.gov (United States)

    Marco-Ramell, Anna; Arroyo, Laura; Peña, Raquel; Pato, Raquel; Saco, Yolanda; Fraile, Lorenzo; Bendixen, Emøke; Bassols, Anna

    2016-11-25

    The objective assessment of animal stress and welfare requires proper laboratory biomarkers. In this work, we have analyzed the changes in serum composition in gilts after switching their housing, from pen to individual stalls, which is generally accepted to cause animal discomfort. Blood and saliva samples were collected a day before and up to four days after changing the housing system. Biochemical analyses showed adaptive changes in lipid and protein metabolism after the housing switch, whereas cortisol and muscular markers showed a large variability between animals. 2D-DIGE and iTRAQ proteomic approaches revealed variations in serum protein composition after changing housing and diet of gilts. Both techniques showed alterations in two main homeostatic mechanisms: the innate immune and redox systems. The acute phase proteins haptoglobin, apolipoprotein A-I and α1-antichymotrypsin 3, and the antioxidant enzyme peroxiredoxin 2 were found differentially expressed by 2D-DIGE. Other proteins related to the innate immune system, including lactotransferrin, protegrin 3 and galectin 1 were also identified by iTRAQ, as well as oxidative stress enzymes such as peroxiredoxin 2 and glutathione peroxidase 3. Proteomics also revealed the decrease of apolipoproteins, and the presence of intracellular proteins in serum, which may indicate physical injury to tissues. Housing of gilts in individual stalls and diet change increase lipid and protein catabolism, oxidative stress, activate the innate immune system and cause a certain degree of tissue damage. We propose that valuable assays for stress assessment in gilts may be based on a score composed by a combination of salivary cortisol, lipid metabolites, innate immunity and oxidative stress markers and intracellular proteins.

  6. Tidal dynamics and their influence on the climate system from the Cretaceous to present day

    Science.gov (United States)

    Weber, Tobias; Thomas, Maik

    2017-11-01

    Global numerical ocean models used for paleo-climate reconstructions commonly only consider the ocean's general circulation but neglect tidal dynamics. However, tidal dynamics affect the ocean's mean general circulation, in particular by vertical mixing and tidal residual mean currents. Through feedback loops the whole climate system is affected. Plate tectonics modify geometric resonance conditions in ocean basins and thereby tidal dynamics. We study the influence of ocean tides on the ocean general circulation and atmospheric parameters by forcing the coupled atmosphere-ocean model ECHAM5/MPIOM with the complete lunisolar tidal potential. Simulations have been performed for five tectonically important time-slices: the Early Albian (ca. 110 million years ago, Ma), the Cenomanian-Turonian Boundary (ca. 93 Ma, CTB), the Early Eocene (ca. 55 Ma), the Early Pliocene (ca. 3.5 Ma), and a pre-industrial period (ca. 1850 CE). The model results suggest that the global mean tidal potential energy in the Early Eocene is almost three times larger than in the CTB. The large potential energy input in the Early Eocene leads to a tripling of current velocities in 10% of the deep ocean. Although the effect of tides on the general ocean circulation is less pronounced in the other time-slices, horizontal velocities are modified by more than 20% in 55% of the deep ocean. The tidally induced shifts of ocean currents and vertical mixing also have an effect on the three-dimensional temperature distribution in the ocean. The impact of tidal dynamics on atmospheric temperatures is particularly strong in the Southern Ocean of the Early Pliocene and the pre-industrial period. By a feedback loop with the atmosphere, tidal forcing locally reduces sea-ice concentration by up to 30% and local atmospheric 2 m temperatures by up to 4°C. Although uncertainties in bathymetry reconstructions limit the significance of quantitative analysis, the qualitative conclusions suggest that the impacts of

  7. Tidal Power Potential in the Submerged Channels of Dar es

    African Journals Online (AJOL)

    Results from in-situ measurements show that currents on the sandbank and the tidal flat, in water depths from 0.5 m to 3.0 m, are directed opposite the main tidal current in the deeper waters. Current velocities vary during a tidal cycle and are strongest in the middle of the cycle. Generally, velocities on the tidal flat are around ...

  8. Tidal Marshes: The Boundary between Land and Ocean.

    Science.gov (United States)

    Gosselink, James

    An overview of the ecology of the tidal marshes along the gulf coast of the United States is presented. The following topics are included: (1) the human impact on tidal marshes; (2) the geologic origins of tidal marshes; (3) a description of the physical characteristics and ecosystem of the marshlands; (4) a description of the marshland food chain…

  9. Field migration rates of tidal meanders recapitulate fluvial morphodynamics.

    Science.gov (United States)

    Finotello, Alvise; Lanzoni, Stefano; Ghinassi, Massimiliano; Marani, Marco; Rinaldo, Andrea; D'Alpaos, Andrea

    2018-02-13

    The majority of tidal channels display marked meandering features. Despite their importance in oil-reservoir formation and tidal landscape morphology, questions remain on whether tidal-meander dynamics could be understood in terms of fluvial processes and theory. Key differences suggest otherwise, like the periodic reversal of landscape-forming tidal flows and the widely accepted empirical notion that tidal meanders are stable landscape features, in stark contrast with their migrating fluvial counterparts. On the contrary, here we show that, once properly normalized, observed migration rates of tidal and fluvial meanders are remarkably similar. Key to normalization is the role of tidal channel width that responds to the strong spatial gradients of landscape-forming flow rates and tidal prisms. We find that migration dynamics of tidal meanders agree with nonlinear theories for river meander evolution. Our results challenge the conventional view of tidal channels as stable landscape features and suggest that meandering tidal channels recapitulate many fluvial counterparts owing to large gradients of tidal prisms across meander wavelengths. Copyright © 2018 the Author(s). Published by PNAS.

  10. Detecting areal changes in tidal flats after sea dike construction ...

    Indian Academy of Sciences (India)

    remote sensing, however, may be used for mapping tidal flats in a rapid and accurate manner. Orbital remote sensing may be used to effectively assess tidal flat accretion due to its repetitive and synop- tic nature (Sanjeevi 1996). Many researchers have used remote sensing images to classify tidal flats and analyze their.

  11. Subtidal flow division at a shallow tidal junction

    NARCIS (Netherlands)

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

  12. 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

  13. Field migration rates of tidal meanders recapitulate fluvial morphodynamics

    Science.gov (United States)

    Finotello, Alvise; Lanzoni, Stefano; Ghinassi, Massimiliano; Marani, Marco; Rinaldo, Andrea; D'Alpaos, Andrea

    2018-02-01

    The majority of tidal channels display marked meandering features. Despite their importance in oil-reservoir formation and tidal landscape morphology, questions remain on whether tidal-meander dynamics could be understood in terms of fluvial processes and theory. Key differences suggest otherwise, like the periodic reversal of landscape-forming tidal flows and the widely accepted empirical notion that tidal meanders are stable landscape features, in stark contrast with their migrating fluvial counterparts. On the contrary, here we show that, once properly normalized, observed migration rates of tidal and fluvial meanders are remarkably similar. Key to normalization is the role of tidal channel width that responds to the strong spatial gradients of landscape-forming flow rates and tidal prisms. We find that migration dynamics of tidal meanders agree with nonlinear theories for river meander evolution. Our results challenge the conventional view of tidal channels as stable landscape features and suggest that meandering tidal channels recapitulate many fluvial counterparts owing to large gradients of tidal prisms across meander wavelengths.

  14. Tidal variations in the Sundarbans Estuarine System, India

    Indian Academy of Sciences (India)

    At all stations, tidal water levels (every. 15 minutes), salinity, water and air temperatures (hourly) were measured over the six tidal cycles. We report the observed spatio-temporal variations of the tidal water level. The predominantly semi-diurnal tides were observed to amplify northwards along each estuary, with the highest ...

  15. Tidal exchange of larvae of Sesarma catenata (Decapoda, Brachyura)

    African Journals Online (AJOL)

    The tidal exchange of larvae of the salt-marsh grapsid crab Sesarma catenata was studied in the Swartkops estuary, a tidally driven, shallow estuary in Algoa Bay, South Africa. Plankton samples were collected bimonlhly during spring and neap tides from October to March at the tidal inlet. Samples were collected hourly for ...

  16. 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

  17. Empirical Tidal Dissipation in Exoplanet Hosts From Tidal Spin-up

    Science.gov (United States)

    Penev, Kaloyan; Bouma, L. G.; Winn, Joshua N.; Hartman, Joel D.

    2018-04-01

    Stars with hot Jupiters (HJs) tend to rotate faster than other stars of the same age and mass. This trend has been attributed to tidal interactions between the star and planet. A constraint on the dissipation parameter {Q}\\star {\\prime } follows from the assumption that tides have managed to spin up the star to the observed rate within the age of the system. This technique was applied previously to HATS-18 and WASP-19. Here, we analyze the sample of all 188 known HJs with an orbital period tidal dissipation parameter ({Q}\\star {\\prime }) increases sharply with forcing frequency, from 105 at 0.5 day‑1 to 107 at 2 day‑1. This helps to resolve a number of apparent discrepancies between studies of tidal dissipation in binary stars, HJs, and warm Jupiters. It may also allow for a HJ to damp the obliquity of its host star prior to being destroyed by tidal decay.

  18. 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...

  19. Sediment Suspension by Straining-Induced Convection at the Head of Salinity Intrusion

    Science.gov (United States)

    Zhang, Qianjiang; Wu, Jiaxue

    2018-01-01

    The tidal straining can generate convective motions and exert a periodic modification of turbulence and sediment transport in estuarine and coastal bottom boundary layers. However, the evidence and physics of convection and sediment suspension induced by tidal straining have not been straightforward. To examine these questions, mooring and transect surveys have been conducted in September 2015 in the region of the Yangtze River plume influence. Field observations and scaling analyses indicate an occurrence of convective motions at the head of saline wedge. Theoretical analyses of stratification evolution in the saline wedge show that unstable stratification and resultant convection are induced by tidal straining. Vertical turbulent velocity and eddy viscosity at the head of saline wedge are both larger than their neutral counterparts in the main body, largely enhancing sediment suspension at the head of saline wedge. Moreover, sediment suspension in both neutral and convection-affected flows is supported by the variance of vertical turbulent velocity, rather than the shearing stress. Finally, the stability correction functions in the Monin-Obukhov similarity theory can be simply derived from the local turbulent kinetic energy balance to successfully describe the effects of tidal straining on turbulent length scale, eddy viscosity, and sediment diffusivity in the convection-affected flow. These recognitions may provide novel understanding of estuarine turbidity maxima, and the dynamical structure and processes for coastal hypoxia.

  20. Nova Scotia Power : in-stream tidal

    International Nuclear Information System (INIS)

    Meade, K.

    2007-01-01

    The Government of Nova Scotia, the Government of New Brunswick, Nova Scotia Power and others have funded a feasibility study of North American sites for commercial instream tidal power. In July 2007, Nova Scotia Power received partial funding for a demonstration project. This presentation provided information on a demonstration plant for tidal power run by Nova Scotia Power. It discussed the benefits of the Open Hydro technology for this plant. In this simple design, the generator is on the circumference of the turbine. The design does not involve any power transmission systems or any pitching of blades. In addition, the technology is environmentally sound as it is completely shrouded, has low rotational speed, and a large open centre allows fish to pass through, and it does not require lubricants. The last benefit that was presented was the scale up of 250 kW machine deployed in a European test facility. The presentation also discussed the advantages of developing tidal power at this time. It was concluded that tidal energy has significant potential. Although it is intermittent, it is predictable and bulk power system can be scheduled to accommodate it. figs

  1. Estuaries and Tidal Marshes. Habitat Pac.

    Science.gov (United States)

    Fish and Wildlife Service (Dept. of Interior), Washington, DC.

    This educational packet consists of an overview, three lesson plans, student data sheets, and a poster. The overview examines estuaries and tidal or salt marshes by discussing the plants and animals in these habitats, marsh productivity, benefits and management of the habitats, historical aspects, and development and pollution. A glossary and list…

  2. Life on the Tidal Mudflats: Elkhorn Slough.

    Science.gov (United States)

    Andresen, Ruth

    Life in an estuarine environment is studied in this set of audio-visual materials prepared for grades 6-12. A 71-frame colored filmstrip, cassette tape narration, and teacher's guide focus upon Elkhorn Slough, a tidal mudflat in the Monterey Bay area, California. Topics examined range from river drainage and the effects of pollution on living…

  3. An optimal tuning strategy for tidal turbines

    Science.gov (United States)

    2016-01-01

    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. PMID:27956870

  4. Palaemon pacijicus (Stimpson) in eastern Cape tidal

    African Journals Online (AJOL)

    1984-09-25

    Sep 25, 1984 ... seasonally with peak numbers and biomass found in summer ... One part of the programme dealt with the tidal pool ... pools sampled. Unicam spectrophotometer at 458 run. A dilution series was made for each batch of concentrate used. A domestic water meter was coupled to the outlet of a portable pump ...

  5. Tidal Energy Dissipation from Topex/Poseidon

    Science.gov (United States)

    Ray, Richard D.; Egbert, G. D.; Smith, David E. (Technical Monitor)

    2000-01-01

    In a recent paper ({\\it Nature, 405,} 775, 2000) we concluded that 25 to 30\\% of the ocean's tidal energy dissipation, or about 1 terawatt, occurs in the deep ocean, with the remaining 2.6 TW in shallow seas. The physical mechanism for deep-ocean dissipation is apparently scattering of the surface tide into internal modes; Munk and Wunsch have suggested that this mechanism may provide half the power needed for mixing the deep-ocean. This paper builds further evidence for $1\\pm 0.2$ TW of deep-ocean dissipation. The evidence is extracted from tidal elevations deduced from seven years of Topex/Poseidon satellite altimeter data. The dissipation rate Is formed as a balance between the rate of working by tidal forces and the energy flux divergence. While dynamical assumptions are required to compute fluxes, area integrals of the energy balance are, owing to the tight satellite constraints, remarkably insensitive to these assumptions. A large suite of tidal solutions based on a wide range of dynamical assumptions, on perturbations to bathymetric models, and on simulated elevation data are used to assess this sensitivity. These and Monte Carlo error fields from a generalized inverse model are used to establish error uncertainties.

  6. The history of tidal power in France

    International Nuclear Information System (INIS)

    Banal, M.

    1997-01-01

    The first known use of tidal power in France concerns the tidal mills in general use during the Middle Age along the French coasts. The first research studies of tidal power plants started at the end of the first world war but it is only in 1940 with the stimulus of Robert Gibrat that was created the Research Society for the use of Tides and the Rance plant project. In 1946, Electricite de France (EdF) started again the studies of this company for a greater size project in the Chausey archipelago which was abandoned for the benefit of the Rance project in the 1960's. The start up of the plant took place in 1967 but the other projects were abandoned during the 1980's. This short paper recalls the historical aspects of the development of tidal power in France and focusses on the research and development studies and on the economical, political and legal factors that led to retain the Rance project among others proposed. (J.S.)

  7. 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

  8. Tidal flat landscape formation and evolution

    NARCIS (Netherlands)

    Hu, Z.

    2015-01-01

    Tidal flat landscape formation and evolution are closely related to the biotic and abiotic processes that take place in the intertidal environments. Extensive studies have been carried out on the relevant agents such as hydrodynamics, sediment transport and the related ecosystem (vegetation and

  9. 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.'

  10. 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.

  11. A new analytical framework for understanding the tidal damping in estuaries

    Science.gov (United States)

    Cai, Huayang; Savenije, Hubert H. G.; Toffolon, Marco

    2013-04-01

    Tidal dynamics in estuaries have long been the subject of intensive scientific interest, particularly to analyse the environmental impact of human interventions. In many estuaries, there are increasing concerns about the impacts on the estuarine environment of, e.g., sea-level rise, water diversion and dredging. However, before predictions about hydraulic responses to future changes can be made with any confidence, there is need to achieve an adequate understanding of tidal wave propagation in estuaries. In this study, we explore different analytical solutions of the tidal hydraulic equations in convergent estuaries. Linear and quasi-nonlinear models are compared for given geometry, friction, and tidal amplitude at the seaward boundary, proposing a common theoretical framework and showing that the main difference between the examined models lies in the treatment of the friction term. A general solution procedure is proposed for the governing equations expressed in dimensionless form, and a new analytical expression for the tidal damping is derived as a weighted average of two solutions, characterized by the usual linearized formulation and the quasi-nonlinear Lagrangean treatment of the friction term (Savenije et al., 2008). The different analytical solutions are tested against fully nonlinear numerical results for a wide range of parameters, and compared with observations in the Scheldt estuary. Overall, the new method compares best with the numerical solution and field data (Cai et al., 2012a). The new accurate relationship for the tidal damping is then exploited for a classification of estuaries based on the distance of the tidally averaged depth from the ideal depth (relative to vanishing amplification) and the critical depth (condition for maximum amplification). Finally, the new model is used to investigate the effect of depth variations on the tidal dynamics in 23 real estuaries, highlighting the usefulness of the analytical method to assess the influence of

  12. TIDAL EVOLUTION OF CLOSE-IN PLANETS

    International Nuclear Information System (INIS)

    Matsumura, Soko; Rasio, Frederic A.; Peale, Stanton J.

    2010-01-01

    Recent discoveries of several transiting planets with clearly non-zero eccentricities and some large obliquities started changing the simple picture of close-in planets having circular and well-aligned orbits. The two major scenarios that form such close-in planets are planet migration in a disk and planet-planet interactions combined with tidal dissipation. The former scenario can naturally produce a circular and low-obliquity orbit, while the latter implicitly assumes an initially highly eccentric and possibly high-obliquity orbit, which are then circularized and aligned via tidal dissipation. Most of these close-in planets experience orbital decay all the way to the Roche limit as previous studies showed. We investigate the tidal evolution of transiting planets on eccentric orbits, and find that there are two characteristic evolution paths for them, depending on the relative efficiency of tidal dissipation inside the star and the planet. Our study shows that each of these paths may correspond to migration and scattering scenarios. We further point out that the current observations may be consistent with the scattering scenario, where the circularization of an initially eccentric orbit occurs before the orbital decay primarily due to tidal dissipation in the planet, while the alignment of the stellar spin and orbit normal occurs on a similar timescale to the orbital decay largely due to dissipation in the star. We also find that even when the stellar spin-orbit misalignment is observed to be small at present, some systems could have had a highly misaligned orbit in the past, if their evolution is dominated by tidal dissipation in the star. Finally, we also re-examine the recent claim by Levrard et al. that all orbital and spin parameters, including eccentricity and stellar obliquity, evolve on a similar timescale to orbital decay. This counterintuitive result turns out to have been caused by a typo in their numerical code. Solving the correct set of tidal

  13. Protoplanetary disc response to distant tidal encounters in stellar clusters

    Science.gov (United States)

    Winter, A. J.; Clarke, C. J.; Rosotti, G.; Booth, R. A.

    2018-04-01

    The majority of stars form in a clustered environment. This has an impact on the evolution of surrounding protoplanetary discs (PPDs) due to either photoevaporation or tidal truncation. Consequently, the development of planets depends on formation environment. Here, we present the first thorough investigation of tidally induced angular momentum loss in PPDs in the distant regime, partly motivated by claims in the literature for the importance of distant encounters in disc evolution. We employ both theoretical predictions and dynamical/hydrodynamical simulations in 2D and 3D. Our theoretical analysis is based on that of Ostriker (1994) and leads us to conclude that in the limit that the closest approach distance xmin ≫ r, the radius of a particle ring, the fractional change in angular momentum scales as (xmin/r)-5. This asymptotic limit ensures that the cumulative effect of distant encounters is minor in terms of its influence on disc evolution. The angular momentum transfer is dominated by the m = 2 Lindblad resonance for closer encounters and by the m = 1, ω = 0 Lindblad resonance at large xmin/r. We contextualize these results by comparing expected angular momentum loss for the outer edge of a PPD due to distant and close encounters. Contrary to the suggestions of previous works, we do not find that distant encounters contribute significantly to angular momentum loss in PPDs. We define an upper limit for closest approach distance where interactions are significant as a function of arbitrary host to perturber mass ratio M2/M1.

  14. Tidal origin of NGC 1427A in the Fornax cluster

    Science.gov (United States)

    Lee-Waddell, K.; Serra, P.; Koribalski, B.; Venhola, A.; Iodice, E.; Catinella, B.; Cortese, L.; Peletier, R.; Popping, A.; Keenan, O.; Capaccioli, M.

    2018-02-01

    We present new HI observations from the Australia Telescope Compact Array and deep optical imaging from OmegaCam on the VLT Survey Telescope of NGC 1427A, an arrow-shaped dwarf irregular galaxy located in the Fornax cluster. The data reveal a star-less HI tail that contains ˜10 per cent of the atomic gas of NGC 1427A as well as extended stellar emission that shed new light on the recent history of this galaxy. Rather than being the result of ram pressure induced star formation, as previously suggested in the literature, the disturbed optical appearance of NGC 1427A has tidal origins. The galaxy itself likely consists of two individual objects in an advanced stage of merging. The HI tail may be made of gas expelled to large radii during the same tidal interaction. It is possible that some of this gas is subject to ram pressure, which would be considered a secondary effect and implies a north-west trajectory of NGC 1427A within the Fornax cluster.

  15. 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

  16. A CLASS OF ECCENTRIC BINARIES WITH DYNAMIC TIDAL DISTORTIONS DISCOVERED WITH KEPLER

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Susan E.; Barclay, Thomas; Howell, Steve B.; Still, Martin; Ibrahim, Khadeejah A. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Everett, Mark [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Mullally, Fergal; Rowe, Jason; Christiansen, Jessie L.; Twicken, Joseph D.; Clarke, Bruce D. [SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, CA 94043 (United States); Kurtz, Donald W.; Hambleton, Kelly, E-mail: susan.e.thompson@nasa.gov [Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom)

    2012-07-01

    We have discovered a class of eccentric binary systems within the Kepler data archive that have dynamic tidal distortions and tidally induced pulsations. Each has a uniquely shaped light curve that is characterized by periodic brightening or variability at timescales of 4-20 days, frequently accompanied by shorter period oscillations. We can explain the dominant features of the entire class with orbitally varying tidal forces that occur in close, eccentric binary systems. The large variety of light curve shapes arises from viewing systems at different angles. This hypothesis is supported by spectroscopic radial velocity measurements for five systems, each showing evidence of being in an eccentric binary system. Prior to the discovery of these 17 new systems, only four stars, where KOI-54 is the best example, were known to have evidence of these dynamic tides and tidally induced oscillations. We perform preliminary fits to the light curves and radial velocity data, present the overall properties of this class, and discuss the work required to accurately model these systems.

  17. Effect of the tidal-seismic resonance

    Science.gov (United States)

    Tian, Y.; Zheng, Y.

    2017-12-01

    For a moon spiraling inward to its planet, the tidal force frequency of a moon is increasing. When the distance of the moon to the planet is close enough, the tidal force frequency can intrude into the frequency range of planet normal modes. Usually the football mode, also known as 0S2, has the lowest frequency. This mode is most likely to be excited and coupled first. When the tidal force has the same frequency with the normal modes, the resonance can happen. The existence of the topography or internal heterogeneities of the planet can have mode coupling. So the energy of gravity force with higher spatial frequencies can be transferred to the low spatial 0S2 mode. The resonant mode 0S2 can exert a negative torque to the rotating moon so its orbit decays. With our 3D numerical boundary element method which takes into account planet surface topography (i.e., Mars as example), we found that the closer the moon is to the planet, the greater falling rate of the moon would be. We applied our method to a planet with equal size of Mars and elastic constants in possible range. The vibration amplitude on the planet surface can reach to the scale of meters when as the moon drop down to about 1.04 radius of the planet to achieve resonance with the 0S2 mode. Our modeling showed that the influence of tidal force caused resonance could not be neglected in the process of moon falling. On the other hand, the resonance may also be able to speed up the accretion of the early forming planet by absorbing the dust of small asteroid nearby by the tidal-seismic resonance.

  18. Light rays and the tidal gravitational pendulum

    Science.gov (United States)

    Farley, A. N. St J.

    2018-05-01

    Null geodesic deviation in classical general relativity is expressed in terms of a scalar function, defined as the invariant magnitude of the connecting vector between neighbouring light rays in a null geodesic congruence projected onto a two-dimensional screen space orthogonal to the rays, where λ is an affine parameter along the rays. We demonstrate that η satisfies a harmonic oscillator-like equation with a λ-dependent frequency, which comprises terms accounting for local matter affecting the congruence and tidal gravitational effects from distant matter or gravitational waves passing through the congruence, represented by the amplitude, of a complex Weyl driving term. Oscillating solutions for η imply the presence of conjugate or focal points along the rays. A polarisation angle, is introduced comprising the orientation of the connecting vector on the screen space and the phase, of the Weyl driving term. Interpreting β as the polarisation of a gravitational wave encountering the light rays, we consider linearly polarised waves in the first instance. A highly non-linear, second-order ordinary differential equation, (the tidal pendulum equation), is then derived, so-called due to its analogy with the equation describing a non-linear, variable-length pendulum oscillating under gravity. The variable pendulum length is represented by the connecting vector magnitude, whilst the acceleration due to gravity in the familiar pendulum formulation is effectively replaced by . A tidal torque interpretation is also developed, where the torque is expressed as a coupling between the moment of inertia of the pendulum and the tidal gravitational field. Precessional effects are briefly discussed. A solution to the tidal pendulum equation in terms of familiar gravitational lensing variables is presented. The potential emergence of chaos in general relativity is discussed in the context of circularly, elliptically or randomly polarised gravitational waves encountering the null

  19. Flow paths of water and sediment in a tidal marsh: relations with marsh developmental stage and tidal inundation height

    NARCIS (Netherlands)

    Temmerman, S.; Bouma, T.J.; Govers, G.; Lauwaet, D.

    2005-01-01

    This study provides new insights in the relative role of tidal creeks and the marsh edge in supplying water and sediments to and from tidal marshes for a wide range of tidal inundation cycles with different high water levels and for marsh zones of different developmental stage. Net import or export

  20. Tidal volume in acute respiratory distress syndrome: how best to select it.

    Science.gov (United States)

    Umbrello, Michele; Marino, Antonella; Chiumello, Davide

    2017-07-01

    Mechanical ventilation is the type of organ support most widely provided in the intensive care unit. However, this form of support does not constitute a cure for acute respiratory distress syndrome (ARDS), as it mainly works by buying time for the lungs to heal while contributing to the maintenance of vital gas exchange. Moreover, it can further damage the lung, leading to the development of a particular form of lung injury named ventilator-induced lung injury (VILI). Experimental evidence accumulated over the last 30 years highlighted the factors associated with an injurious form of mechanical ventilation. The present paper illustrates the physiological effects of delivering a tidal volume to the lungs of patients with ARDS, and suggests an approach to tidal volume selection. The relationship between tidal volume and the development of VILI, the so called volotrauma, will be reviewed. The still actual suggestion of a lung-protective ventilatory strategy based on the use of low tidal volumes scaled to the predicted body weight (PBW) will be presented, together with newer strategies such as the use of airway driving pressure as a surrogate for the amount of ventilatable lung tissue or the concept of strain, i.e., the ratio between the tidal volume delivered relative to the resting condition, that is the functional residual capacity (FRC). An ultra-low tidal volume strategy with the use of extracorporeal carbon dioxide removal (ECCO 2 R) will be presented and discussed. Eventually, the role of other ventilator-related parameters in the generation of VILI will be considered (namely, plateau pressure, airway driving pressure, respiratory rate (RR), inspiratory flow), and the promising unifying framework of mechanical power will be presented.

  1. Tidal Love numbers and moment-Love relations of polytropic stars

    Science.gov (United States)

    Yip, Kenny L. S.; Leung, P. T.

    2017-12-01

    The physical significance of tidal deformation in astronomical systems has long been known. The recently discovered universal I-Love-Q relations, which connect moment of inertia, quadrupole tidal Love number and spin-induced quadrupole moment of compact stars, also underscore the special role of tidal deformation in gravitational wave astronomy. Motivated by the observation that such relations also prevail in Newtonian stars and crucially depend on the stiffness of a star, we consider the tidal Love numbers of Newtonian polytropic stars whose stiffness is characterized by a polytropic index n. We first perturbatively solve the Lane-Emden equation governing the profile of polytropic stars through the application of the scaled delta expansion method and then formulate perturbation series for the multipolar tidal Love number about the two exactly solvable cases with n = 0 and n = 1, respectively. Making use of these two series to form a two-point Padé approximant, we find an approximate expression of the quadrupole tidal Love number, whose error is less than 2.5 × 10-5 per cent (0.39 per cent) for n ∈ [0, 1] (n ∈ [0, 3]). Similarly, we also determine the mass moments for polytropic stars accurately. Based on these findings, we are able to show that the I-Love-Q relations are in general stationary about the incompressible limit irrespective of the equation of state of a star. Moreover, for the I-Love-Q relations, there is a secondary stationary point near n ≈ 0.4444, thus showing the insensitivity to n for n ∈ [0, 1]. Our investigation clearly tracks the universality of the I-Love-Q relations from their validity for stiff stars such as neutron stars to their breakdown for soft stars.

  2. 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.

  3. Tidal regimes and salt marshes - the River Hamble analogue

    International Nuclear Information System (INIS)

    Gray, A.J.; Moy, I.L.; Warman, E.A.; Dawson, F.H.; Henville, P.

    1993-01-01

    Construction of estuarine tidal-energy barrages has a potentially major effect on the tidal regime of the estuary, particularly upstream of a barrage. Because tidal regime largely controls the distribution and species composition of intertidal plant and animal communities, it is important to understand how barrages may affect such communities. The main objectives of the research described in this report were to relate recent changes in tidal regime within an embanked area of salt marsh and mudflat to changes in the distribution of plant species. This was to test predictions about tidal control of species' range and to assess the site's suitability as an analogue of post-barrage conditions. (author)

  4. Pressure-gradient-driven nearshore circulation on a beach influenced by a large inlet-tidal shoal system

    Science.gov (United States)

    Shi, F.; Hanes, D.M.; Kirby, J.T.; Erikson, L.; Barnard, P.; Eshleman, J.

    2011-01-01

    The nearshore circulation induced by a focused pattern of surface gravity waves is studied at a beach adjacent to a major inlet with a large ebb tidal shoal. Using a coupled wave and wave-averaged nearshore circulation model, it is found that the nearshore circulation is significantly affected by the heterogeneous wave patterns caused by wave refraction over the ebb tidal shoal. The model is used to predict waves and currents during field experiments conducted near the mouth of San Francisco Bay and nearby Ocean Beach. The field measurements indicate strong spatial variations in current magnitude and direction and in wave height and direction along Ocean Beach and across the ebb tidal shoal. Numerical simulations suggest that wave refraction over the ebb tidal shoal causes wave focusing toward a narrow region at Ocean Beach. Due to the resulting spatial variation in nearshore wave height, wave-induced setup exhibits a strong alongshore nonuniformity, resulting in a dramatic change in the pressure field compared to a simulation with only tidal forcing. The analysis of momentum balances inside the surf zone shows that, under wave conditions with intensive wave focusing, the alongshore pressure gradient associated with alongshore nonuniform wave setup can be a dominant force driving circulation, inducing heterogeneous alongshore currents. Pressure-gradient- forced alongshore currents can exhibit flow reversals and flow convergence or divergence, in contrast to the uniform alongshore currents typically caused by tides or homogeneous waves.

  5. Tidal disruption of fuzzy dark matter subhalo cores

    Science.gov (United States)

    Du, Xiaolong; Schwabe, Bodo; Niemeyer, Jens C.; Bürger, David

    2018-03-01

    We study tidal stripping of fuzzy dark matter (FDM) subhalo cores using simulations of the Schrödinger-Poisson equations and analyze the dynamics of tidal disruption, highlighting the differences with standard cold dark matter. Mass loss outside of the tidal radius forces the core to relax into a less compact configuration, lowering the tidal radius. As the characteristic radius of a solitonic core scales inversely with its mass, tidal stripping results in a runaway effect and rapid tidal disruption of the core once its central density drops below 4.5 times the average density of the host within the orbital radius. Additionally, we find that the core is deformed into a tidally locked ellipsoid with increasing eccentricities until it is completely disrupted. Using the core mass loss rate, we compute the minimum mass of cores that can survive several orbits for different FDM particle masses and compare it with observed masses of satellite galaxies in the Milky Way.

  6. Accuracy of near-patient vs. inbuilt spirometry for monitoring tidal volumes in an in-vitro paediatric lung model.

    Science.gov (United States)

    Morgenroth, S; Thomas, J; Cannizzaro, V; Weiss, M; Schmidt, A R

    2018-03-01

    Spirometric monitoring provides precise measurement and delivery of tidal volumes within a narrow range, which is essential for lung-protective strategies that aim to reduce morbidity and mortality in mechanically-ventilated patients. Conventional anaesthesia ventilators include inbuilt spirometry to monitor inspiratory and expiratory tidal volumes. The GE Aisys CS 2 anaesthesia ventilator allows additional near-patient spirometry via a sensor interposed between the proximal end of the tracheal tube and the respiratory tubing. Near-patient and inbuilt spirometry of two different GE Aisys CS 2 anaesthesia ventilators were compared in an in-vitro study. Assessments were made of accuracy and variability in inspiratory and expiratory tidal volume measurements during ventilation of six simulated paediatric lung models using the ASL 5000 test lung. A total of 9240 breaths were recorded and analysed. Differences between inspiratory tidal volumes measured with near-patient and inbuilt spirometry were most significant in the newborn setting (p tidal volume measurements with near-patient spirometry were consistently more accurate than with inbuilt spirometry for all lung models (p tidal volumes decreased with increasing tidal volumes, and was smaller with near-patient than with inbuilt spirometry. The variability in measured tidal volumes was higher during expiration, especially with inbuilt spirometry. In conclusion, the present in-vitro study shows that measurements with near-patient spirometry are more accurate and less variable than with inbuilt spirometry. Differences between measurement methods were most significant in the smallest patients. We therefore recommend near-patient spirometry, especially for neonatal and paediatric patients. © 2018 The Association of Anaesthetists of Great Britain and Ireland.

  7. Tidal Friction in the Earth and Ocean

    Science.gov (United States)

    Ray, R. D.

    2006-12-01

    "Tidal Friction" is a classic subject in geophysics, with ties to some of the great scientists of the Victorian era. The subject has been reinvigorated over the past decade by space geodesy, and particularly by the Topex/Poseidon satellite altimeter mission. In fact, the topic has now taken on some significance in oceanography, with potential implications for problems of mixing, thermocline maintenance, and the thermohaline circulation. Likewise, tidal measurements have become sufficiently precise to reveal new information about the solid earth. In this respect, the tidal force is an invaluable "probe" of the earth, at frequencies well outside the seismic band. This talk will "follow the energy" of tides while noting some important geophysical implications at each stage. In the present earth-moon-sun configuration, energy for tides is extracted from the earth's rotation. Ancient eclipses bear witness to this, and the discrepancy between Babylonian (and other) observations and tidal predictions yields unique information about the mantle and the overlying fluid envelope. Complementary information comes from tidal anelasticity estimates, which are now available at frequencies ranging from semidiurnal to fortnightly, monthly, and 18.6 years. These data, when combined with various kinds of gravity measurements, are relevant to the present-day sea-level problem. Solid-earth tidal dissipation represents less than 5% of the system total. As has long been realized, the largest energy sink is the ocean. About 70% of the oceanic dissipation occurs in shallow seas (the traditional sink) and 30% in the deep ocean, generally near rugged bottom topography. The latter represents a substantial amount of power, roughly 1 gigawatt, available for generation of internal tides and other baroclinic motions. Experiments like HOME are helping unravel the links between barotropic tides, internal tides, turbulence, and mixing. The latter opens possible linkages to climate, and recent work

  8. Tidal power dams in the Bay of Fundy

    International Nuclear Information System (INIS)

    Walsun, W. van

    1998-01-01

    The challenges of harnessing tidal power and the construction of dams and tidal power plants in a tidal-ocean environment such as the Bay of Fundy in New Brunswick are discussed. In the 1966-1988 series of studies, three sites were chosen at the Bay of Fundy as being the most promising, namely (1) site B9 in Minas Basin at the entrance to Cobequid Bay, (2) site A8 at the narrow neck beyond the entrance to Cumberland Basin, and (3) site A6 at the entrance to Shepody Bay. All the sites are located at the head of the Bay of Fundy because that is where the maximum tidal ranges are found and a basin's tidal energy potential is proportional to the square of its tidal range. Site B9 was determined to have the greatest tidal power potential but no plant has ever been built because reports have stated that a solid conventional tidal power barrage at site B9 would increase the tidal range at Boston by as much as 30 cm. Rather than abandoning the site for this reason, an installation consisting of a series of piers from shore to shore with hydraulic turbines mounted in the spaces between piers, was suggested. A simple mathematical model has been developed for determining the operation of this tidal fence. The cost of energy, generated by the tidal fence at site B9 was also calculated. Further studies are suggested to determine the exact environmental effect of the tidal fence on the tidal regime. If environmental problems persist, machines with larger discharge capabilities could be considered to reduce the interference of the fence with natural tidal movements. 9 refs., 6 figs

  9. Suspended and bedload dynamics in a tidally influenced river: the river Dyfi, Wales, UK.

    Science.gov (United States)

    Brewer, P. A.; Vericat, D.; Baas, J. H.; Jago, C. F.; Brasington, J.; Wheaton, J. M.; Causer, F.

    2007-12-01

    transport in tidal cycles, although very fine gravels were moved during high spring tides. Mineralogical, geochemical and particle size analyses are revealing contrasting sediment provenance dynamics during river floods and tidal cycles. These data will be used to establish the relative frequencies, magnitudes and flux directions of components of the seasonal sediment budget due to tide and river currents.

  10. Tidal Disruption Events from Eccentric Nuclear Disks

    Science.gov (United States)

    Wernke, Heather N.; Madigan, Ann-Marie

    2018-04-01

    Stars that get too close to a supermassive black hole are in danger of being tidally disrupted. Stellar two-body relaxation is commonly assumed to be the main driver of these events. Recent work has shown, however, that secular gravitational torques from eccentric nuclear disks can push stars to extreme eccentricities at much higher rates than predicted by two-body relaxation. This work did not include the effects of general relativity, however, which could quench secular torques via rapid apsidal precession. Here we show that, for a star in danger of disruption, general relativity acts on a timescale of less than an orbital period. This short timescale means that general relativity does not have enough time to have a major effect on the orbit. When driven by secular torques from eccentric nuclear disks, tidal disruption event rates are not affected by general relativity.

  11. 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.

  12. Capturing American black ducks in tidal waters

    Science.gov (United States)

    Harrison, M.K.; Haramis, G.M.; Jorde, Dennis G.; Stotts, D.B.

    2000-01-01

    We modified conventional, funnel-entrance dabbling duck bait traps to increase captures for banding of American Black Ducks (Anas rubripes) in tidal saltmarsh habitats of Smith Island, Maryland, one of the few remaining strongholds for breeding Black Ducks in the Chesapeake Bay. Traps and trapping techniques were adapted to tidal creeks and refined to improve capture rate, reduce mortality, and minimize interference by gulls. Best results were achieved by synchronizing trapping with predawn, low-tide foraging patterns of Black Ducks. Trap entrances were critical to retaining ducks, and use of loafing platforms reduced overall mortality to 3% of captures per year. We captured 3071 Black Ducks during the 14-year period, 1984-199

  13. Detecting Globular Star Cluster Tidal Streams

    Science.gov (United States)

    Powell, William Lee, Jr.; Wilhelm, Ronald; Lauchner, Adam; McWilliam, Andrew

    2006-10-01

    Globular cluster tidal streams are of interest for what they can tell us of the dynamical evolution of the clusters and of our Galaxy. Recent studies have used photometric and statistical subtraction methods to attempt to separate potential streams from the field stars that contaminate the samples. As our primary method we choose instead to use photometry to select blue stars that match the horizontal branch of the clusters. We then make spectroscopic observations of these candidates to determine their metallicities and radial velocities, which further constrains whether the candidate stars really originated in the cluster. Combining these results with the photometric data offers a better picture of the structure of tidal streams, and allows comparison of detected stars to theoretical predictions. We present preliminary photometric and spectroscopic results. Data obtained at McDonald Observatory, Kitt Peak National Observatory, and Las Campanas Observatory.

  14. Globular Cluster Tidal Streams: An Observational Study

    Science.gov (United States)

    Powell, William L.; Lauchner, A.; Wilhelm, R.; McWilliam, A.

    2006-12-01

    Globular cluster tidal streams are of interest for what they can tell us of the dynamical evolution of the clusters and of our Galaxy. Recent studies have used photometric and statistical subtraction methods to attempt to separate potential streams from the field stars that contaminate the samples. We chose instead as our primary method to use photometry to select blue stars that match the horizontal branch of the clusters. We then make spectroscopic observations of these candidates to determine their metallicity and radial velocities. Combining these results with the photometric data offers a better picture of the structure and validity of tidal streams. We present photometric and spectroscopic results for several globular clusters and their surrounding fields. Data were obtained at McDonald Observatory, Kitt Peak, and Las Campanas Observatory. SDSS data were also used. WLP acknowledges the support of a Sigma Xi Grant-In-Aid of research. RW acknowledges the support of a AAS Small Research Grant.

  15. Two Sides of the Same Coin: ERP and Wavelet Analyses of Visual Potentials Evoked and Induced by Task-Relevant Faces

    Science.gov (United States)

    Van der Lubbe, Rob H. J.; Szumska, Izabela; Fajkowska, Małgorzata

    2016-01-01

    New analysis techniques of the electroencephalogram (EEG) such as wavelet analysis open the possibility to address questions that may largely improve our understanding of the EEG and clarify its relation with related potentials (ER Ps). Three issues were addressed. 1) To what extent can early ERERP components be described as transient evoked oscillations in specific frequency bands? 2) Total EEG power (TP) after a stimulus consists of pre-stimulus baseline power (BP), evoked power (EP), and induced power (IP), but what are their respective contributions? 3) The Phase Reset model proposes that BP predicts EP, while the evoked model holds that BP is unrelated to EP; which model is the most valid one? EEG results on NoGo trials for 123 individuals that took part in an experiment with emotional facial expressions were examined by computing ERPs and by performing wavelet analyses on the raw EEG and on ER Ps. After performing several multiple regression analyses, we obtained the following answers. First, the P1, N1, and P2 components can by and large be described as transient oscillations in the α and θ bands. Secondly, it appears possible to estimate the separate contributions of EP, BP, and IP to TP, and importantly, the contribution of IP is mostly larger than that of EP. Finally, no strong support was obtained for either the Phase Reset or the Evoked model. Recent models are discussed that may better explain the relation between raw EEG and ERPs. PMID:28154612

  16. 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.

  17. Integrating tidal and nontidal ecological assessments

    Science.gov (United States)

    Mark Southerland; Roberto Llanso

    2016-01-01

    The Maryland Department of Natural Resources (DNR) has a long history of conducting rigorous assessments of ecological conditions in both tidal and nontidal waters. The Long-Term Benthic (LTB) Monitoring Program and the Maryland Biological Stream Survey (MBSS) both use reference-based indicators of benthic invertebrate communities to provide areawide estimates of ...

  18. Tidal power from the River Mersey

    International Nuclear Information System (INIS)

    1991-01-01

    The studies described in this report relate to work carried out since those reported upon in the stage I Mersey Barrage Report on the possible construction of a tidal power barrage on the Mersey Estuary. The objectives of the work were to review basic engineering, re-assess cost and energy output, improve engineering configuration, quantify social, industrial and regional effects, determine preferred alignment, review the main environmental impacts, assess economic viability and financing and identify further study requirements. (UK)

  19. Tidal heating in multilayered terrestrial exoplanets

    International Nuclear Information System (INIS)

    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 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.

  20. Capture of Small Bodies After Tidal Disruption

    Science.gov (United States)

    Ershova, A.; Medvedev, Yu.

    2017-09-01

    The subject of the current work is the phisical and dynamical evolution of the small comets group formed by tidal disruption of the protocomet while passing near the large body (Sun, Jupiter). The equations of motion were integrated numericaly. In case of the Sun the evolution of the sun-grazing orbits were discussed and the typical lifetime of such comets was estimated. Nongravitational acceleration and the size reduction of fragments due to sublimation were taking into account using the Marsden formula.

  1. 4G/5G variant of plasminogen activator inhibitor-1 gene and severe pregnancy-induced hypertension: subgroup analyses of variants of angiotensinogen and endothelial nitric oxide synthase.

    Science.gov (United States)

    Kobashi, Gen; Ohta, Kaori; Yamada, Hideto; Hata, Akira; Minakami, Hisanori; Sakuragi, Noriaki; Tamashiro, Hiko; Fujimoto, Seiichiro

    2009-01-01

    Pregnancy-induced hypertension (PIH) is a common cause of perinatal mortality. It is believed to result from the interaction of several factors, including those related to the blood coagulation system. We performed genotyping and subgroup analyses to determine if the 4G/5G genotypes of the plasminogen activator inhibitor-1 gene (PAI-1) play a role in the pathogenesis of PIH, and to evaluate possible interactions of the PAI-1 polymorphisms with those of the angiotensinogen gene (AGT) and the endothelial nitric oxide synthase gene (NOS3). An association study of PAI-1 polymorphism, and subgroup analyses of common variants of AGT and NOS3, among 128 patients with PIH and 376 healthy pregnant controls. No significant differences were found between the cases and controls in the frequencies of allele 4G or the 4G/4G genotype. In subgroup analyses, after adjustment for multiple comparison, a significant association with the AGT TT genotype was found among women with the PAI-1 4G/4G genotype, and an association with the NOS3 GA+AA genotype was found among women with the 5G/5G or 4G/5G genotypes. Our findings suggest that there are at least 2 pathways in the pathogenesis of severe PIH. However, with respect to early prediction and prevention of severe PIH, although the PAI-1 4G/4G genotype alone was not a risk factor for severe PIH, the fact that PAI-1 genotypes are associated with varying risks for severe PIH suggests that PAI-1 genotyping of pregnant women, in combination with other tests, may be useful in the development of individualized measures that may prevent severe PIH.

  2. Tidal controls on river delta morphology

    Science.gov (United States)

    Hoitink, A. J. F.; Wang, Z. B.; Vermeulen, B.; Huismans, Y.; Kästner, K.

    2017-09-01

    River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world’s largest deltas intensifies. Harbour development, construction of flood defences, sand mining and land reclamation emerge as key contemporary factors that exert an impact on delta morphology. Tides interacting with river discharge can play a crucial role in the morphodynamic development of deltas under pressure. Emerging insights into tidal controls on river delta morphology suggest that--despite the active morphodynamics in tidal channels and mouth bar regions--tidal motion acts to stabilize delta morphology at the landscape scale under the condition that sediment import during low flows largely balances sediment export during high flows. Distributary channels subject to tides show lower migration rates and are less easily flooded by the river because of opposing non-linear interactions between river discharge and the tide. These interactions lead to flow changes within channels, and a more uniform distribution of discharge across channels. Sediment depletion and rigorous human interventions in deltas, including storm surge defence works, disrupt the dynamic morphological equilibrium and can lead to erosion and severe scour at the channel bed, even decades after an intervention.

  3. A simple analytical expression to describe tidal damping or amplification

    Science.gov (United States)

    Savenije, H. H. G.

    2001-03-01

    Can a single line describe tidal damping or amplification? Tidal damping and amplification in alluvial estuaries are constrained by an implicit feedback mechanism. The time lag ɛ between the occurrence of high water and high water slack is crucial in this regard. An analytical solution of the St. Venant equations appears to result in a surprisingly simple explicit relation for the tidal range, consisting of an exponential and a linear term. In alluvial estuaries, the linear term is dominant, particularly in the case of tidal amplification. In the case of tidal damping the exponential term only becomes important in the upper reaches of the estuary (preventing the expression for the tidal range from becoming negative). In tidal amplification, the exponential term is suppressed by the newly defined tidal Froude Number which (as it contains sin ɛ) tends to zero when the tidal wave gets a predominantly standing wave character. This negative feedback prevents the development of an exponentially increasing tidal range. Finally, the expression obtained is a very useful explicit equation to determine estuary parameters that are difficult to determine from direct observations, such as the roughness and the mean water depth.

  4. The effect of tidal heating on core dynamos in the TRAPPIST-1 system

    Science.gov (United States)

    Knapp, Mary; Stamenkovic, Vlada

    2017-05-01

    The recent discovery of seven Earth-sized planets orbiting a nearby (12 pc) M8 dwarf TRAPPIST-1 (T1) presents the best opportunity yet to study the magnetic fields of small exoplanets. The T1 planets likely experience significant tidal heating due to their interaction with each other as well as their host star. The system bears a striking resemblance to an expanded version of the Galilean moons of the Jovian system. This similarity suggests that there may be magnetic interaction between the inner T1 planets and the host star, similar to Io and its flux tube, Europa's induced magnetic field, and Ganymede's intrinsic dynamo field. This work examines whether tidal effects enhance or suppress magnetic field generation in the T1 planets. Existing interior models developed in Stamenkovic et al. (2012) are adapted to include tidal heating and tailored specifically to the T1 planets in order to determine whether the interior energetics are favorable or unfavorable to a sustained magnetic dynamo over the lifetime of the system. Allowing for a range of planetary input parameters (core fraction, bulk composition, initial temperature, etc.), we quantify the influence of tidal heating on the likelihood of sustained core dynamos in the T1 planets.

  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. Reactive power control and optimisation of hybrid off shore tidal turbine with system uncertainties

    Directory of Open Access Journals (Sweden)

    Asit Mohanty

    2016-12-01

    Full Text Available This paper projects an isolated hybrid model of Offshore wind-diesel-tidal turbine and discusses the stability and reactive power management issue of the whole system. The hybrid system often loses its stability as it becomes prone to uncertain load and input parameters and therefore the necessity of Reactive power management becomes necessary. The overall stability of the hybrid offshore wind-diesel-tidal turbine is made possible by the management of reactive power in the hybrid system through the application of FACTS devices. And therefore the dynamic hybrid model of the DFIG and DDPMSG based offshore wind-diesel-tidal turbine is analysed for stability with different input parameters like wind and tidal energies. For detailed modelling and simulation, a small signal model of the whole hybrid system is designed and reactive power management of the system is achieved by the incorporation of a STATCOM controller. For improvement of stability and reactive power compensation of the hybrid system, GA and PSO optimised STATCOM controller is used.

  7. Satellite Tidal Magnetic Signals Constrain Oceanic Lithosphere-Asthenosphere Boundary Earth Tomography with Tidal Magnetic Signals

    Science.gov (United States)

    Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.; Sabaka, Terence J.; Chandrasekharan, Manoj; Olsen, Niles

    2016-01-01

    The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation of secondary 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. Here 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. The model derived from more than 12 years of satellite data reveals an Approximately 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.

  8. An integrated study of natural hydroxyapatite-induced osteogenic differentiation of mesenchymal stem cells using transcriptomics, proteomics and microRNA analyses

    International Nuclear Information System (INIS)

    Zhang, Zhiwei; Wang, Jiandan; Lü, Xiaoying

    2014-01-01

    This work combined transcriptomics, proteomics, and microRNA (miRNA) analyses to elucidate the mechanism of natural hydroxyapatite (NHA)-induced osteogenic differentiation of mesenchymal stem cells (MSCs). First, NHA powder was obtained from pig bones and fabricated into disc-shaped samples. Subsequently, the proliferation and osteogenic differentiation of MSCs cultured on NHA were investigated. Then, proteomics was employed to detect the protein expression profiles of MSCs cultured on NHA, and the effect of NHA on MSCs was analyzed through an integrated pathway analysis (including proteomics and previous transcriptomics data) in which specific NHA-induced differentiation pathways were analyzed. The pathway nodes with expression data at both the mRNA and protein levels (mRNA–protein pairs) were filtered in differentiation-related pathways. miRNAs corresponding to these target mRNA–protein pairs were predicted, screened and tested, and the regulatory effects of miRNAs on mRNA–protein pairs were analyzed. Finally, the NHA-induced osteogenic pathways were verified. The results of an MTT assay and alkaline phosphatase (ALP) staining showed that the cell proliferation rate decreased and the osteogenic performance improved in the presence of NHA. By integrating transcriptomics and proteomics, the genes and proteins involved in 89 pathways were shown to be differentially expressed. Among them, 5 differentiation-associated pathways, in which 9 miRNAs and 8 regulated-target mRNA–protein zby inhibiting the target mRNA–protein pair HSPA8 in the MAPK signaling pathway, and miR-26a and miR-26b might inhibit adipogenic differentiation by repressing the target mRNA–protein pair HMGA1 in the adipogenesis pathway. A verification experiment for the osteogenic pathway indicated that the ERK1/2 or JNK MAPK pathways might play an important role in NHA-induced osteogenic differentiation. In conclusion, NHA affected MSCs at both the transcriptional and translational levels

  9. Low tidal volume protects pulmonary vasomotor function from “second-hit” injury in acute lung injury rats

    Directory of Open Access Journals (Sweden)

    Pan Chun

    2012-09-01

    Full Text Available Abstract Background Sepsis could induce indirect acute lung injury(ALI, and pulmonary vasomotor dysfunction. While low tidal volume is advocated for treatment of ALI patients. However, there is no evidence for low tidal volume that it could mitigate pulmonary vasomotor dysfunction in indirect ALI. Our study is to evaluate whether low tidal volume ventilation could protect the pulmonary vascular function in indirect lipopolysaccharide (LPS induced acute lung injury rats. Methods An indirect ALI rat model was induced by intravenous infusion of LPS. Thirty rats (n = 6 in each group were randomly divided into (1Control group; (2 ALI group; (3 LV group (tidal volume of 6mL/kg; (4 MV group (tidal volume of 12mL/kg; (5VLV group (tidal volume of 3mL/kg. Mean arterial pressure and blood gas analysis were monitored every 2 hours throughout the experiment. Lung tissues and pulmonary artery rings were immediately harvested after the rats were bled to be killed to detect the contents of endothelin-1 (ET-1, endothelial nitric oxide synthase (eNOS and TNF-α. Acetylcholine (Ache-induced endothelium-dependent and sodium nitroprusside (SNP-induced endothelium-independent relaxation of isolated pulmonary artery rings were measured by tensiometry. Results There was no difference within groups concerning blood pressure, PaCO2 and SNP-induced endothelium-independent relaxation of pulmonary artery rings. Compared with MV group, LV group significantly reduced LPS-induced expression of ET-1 level (113.79 ± 7.33pg/mL vs. 152.52 ± 12.75pg/mL, P P P -7mol/L-10-4mol/L-induced vasodilatation was ameliorated 30% more in LV group than in MV group. Conclusions Low tidal volume could protect the pulmonary vasodilative function during indirect ALI by decreasing vasoconstrictor factors, increasing expressions of vasodilator factors in pulmonary endothelial cells, and inhibiting inflammation injuries.

  10. How Cassini can constrain tidal dissipation in Saturn

    Science.gov (United States)

    Luan, Jing; Fuller, Jim; Quataert, Eliot

    2018-02-01

    Tidal dissipation inside giant planets is important for the orbital evolution of their natural satellites. It is conventionally treated by parametrized equilibrium tidal theory, in which the tidal torque declines rapidly with distance, and orbital expansion was faster in the past. However, some Saturnian satellites are currently migrating outward faster than predicted by equilibrium tidal theory. Resonance locking between satellites and internal oscillations of Saturn naturally matches the observed migration rates. Here, we show that the resonance locking theory predicts dynamical tidal perturbations to Saturn's gravitational field in addition to those produced by equilibrium tidal bulges. We show that these perturbations can likely be detected during Cassini's proximal orbits if migration of satellites results from resonant gravity modes, but will likely be undetectable if migration results from inertial wave attractors or dissipation of the equilibrium tide. Additionally, we show that the detection of gravity modes would place constraints on the size of the hypothetical stably stratified region in Saturn.

  11. Similarity conditions for investigations of hydraulic-thermal tidal models

    International Nuclear Information System (INIS)

    Fluegge, G.; Schwarze, H.

    1975-01-01

    With the construction of nuclear power plants near German tidal estuaries in mind, investigations of mixing and spreading processes which occur during the discharge of heated cooling water in tidal waters were carried out in hydraulic-thermal tidal models of the Lower Weser and Lower Elbe by the Franzius Institute for hydraulic and coastal engineering of the Technical University Hannover. This contribution discusses in detail the problems met and the experience gained in constructing and operating these models. (orig./TK) [de

  12. Tidal effects on groundwater contamination at Pekan, Pahang

    International Nuclear Information System (INIS)

    Nor Dalila Desa; Dominic, J.A.; Mohd Muzamil Mohd Hashim; Kamarudin Samuding; Mohd Faizun Khalid; Mod Omar Hassan; Kamaruzaman Mohamad

    2014-01-01

    The meeting of coastal ground water and the sea is a unique and dynamic hydro geologic boundary phenomenon that has fascinated groundwater engineers and scientists for the past century. The variation of seawater level resulting from tidal fluctuations is usually neglected in regional groundwater flow studies. In this study the effects of seawater tidal on groundwater are investigated using geophysical together with conventional method. Comparative result between these two methods shown how tidal fluctuations effects groundwater in study area. (author)

  13. Suspended sediment transport trough a large fluvial-tidal channel network

    Science.gov (United States)

    Wright, Scott A.; Morgan-King, Tara L.

    2015-01-01

    The confluence of the Sacramento and San Joaquin Rivers, CA, forms a large network of interconnected channels, referred to as the Sacramento-San Joaquin Delta (the Delta). The Delta comprises the transition zone from the fluvial influences of the upstream rivers and tidal influences of San Francisco Bay downstream. Formerly an extensive tidal marsh, the hydrodynamics and geomorphology of Delta have been substantially modified by humans to support agriculture, navigation, and water supply. These modifications, including construction of new channels, diking and draining of tidal wetlands, dredging of navigation channels, and the operation of large pumping facilities for distribution of freshwater from the Delta to other parts of the state, have had a dramatic impact on the physical and ecological processes within the Delta. To better understand the current physical processes, and their linkages to ecological processes, the USGS maintains an extensive network of flow, sediment, and water quality gages in the Delta. Flow gaging is accomplished through use of the index-velocity method, and sediment monitoring uses turbidity as a surrogate for suspended-sediment concentration. Herein, we present analyses of the transport and dispersal of suspended sediment through the complex network of channels in the Delta. The primary source of sediment to the Delta is the Sacramento River, which delivers pulses of sediment primarily during winter and spring runoff events. Upon reaching the Delta, the sediment pulses move through the fluvial-tidal transition while also encountering numerous channel junctions as the Sacramento River branches into several distributary channels. The monitoring network allows us to track these pulses through the network and document the dominant transport pathways for suspended sediment. Further, the flow gaging allows for an assessment of the relative effects of advection (the fluvial signal) and dispersion (from the tides) on the sediment pulses as they

  14. Comparison of tidal strain changes observed at the borehole array observation system with in situ rock properties in the Tono region, central Japan

    Science.gov (United States)

    Asai, Yasuhiro; Ishii, Hiroshi; Aoki, Harumi

    2009-12-01

    We have developed a digital multi-component borehole instrument for boreholes deeper than 1 km and with diameters smaller than 98 mm, and installed it at the bottom of seven deep boreholes in the Tono region, central Japan. So far, our borehole instruments have observed not only tidal signals, but also strain-steps associated with large earthquakes, and environmentally induced signals. In this study, we analyze the strain data from four observation sites using the tidal analysis program BAYTAP-G and compare the tidal amplitudes of strain with in situ rock properties. We observed an obvious difference in amplitude and phase of the M2 and O1 tidal strains from four observation sites that are located in the same Toki granite bedrock within a distance of 10 km. There are strong negative correlations between the semi-diurnal E-W, areal tidal strain and in situ rock hardness (shear modulus and Young's modulus), while N-S tidal strain is unrelated. In contrast, strain-steps associated with large earthquakes increase with hardness, as observed at two sites. We consider that the inconsistency of the behavior of the tidal amplitudes and strain-steps may be caused by the heterogeneity of rocks near the borehole strainmeters.

  15. New estimates of oceanic tidal energy dissipation from satellite altimetry

    Science.gov (United States)

    Cartwright, David E.; Ray, Richard D.

    1989-01-01

    As a novel approach to computing the flux of tidal power into shelf areas, tidal maps of an oceanic area near the Patagonian Shelf are derived from 11 months of altimetry records from the GEOSAT satellite. Power fluxes are computed from the maps through Laplace's tidal equations. Flux vectors for M2 clearly show a convergence on to the southern portion of the shelf sea and their total is nearly twice the loss computed by Miller for that area. A decrease of 'quality factor' with frequency from M2 to S2 is in keeping with Webb's hypothesis of shelf resonances at frequencies a little higher than the tidal band.

  16. Turbulent viscosity and Jupiter's tidal Q. [energy dissipation function

    Science.gov (United States)

    Goldreich, P.; Nicholson, P. D.

    1977-01-01

    A recent estimate of tidal dissipation by turbulent viscosity in Jupiter's convective interior predicts that the current value of the planet's tidal Q is roughly 5 million. We point out a fundamental error in this calculation, and show that turbulent dissipation alone implies that at present Q is about 50 trillion. Our reduced estimate for the rate of tidal dissipation shows conclusively that tidal torques have produced only negligible modifications of the orbits of the Galilean satellites over the age of the solar system.

  17. Influence of tidal parameters on SeaGen flicker performance.

    Science.gov (United States)

    MacEnri, Joseph; Reed, Matthew; Thiringer, Torbjörn

    2013-02-28

    This paper presents the analysis of the study of the flicker emitted from the 1.2 MW tidal energy converter (TEC), SeaGen, against varying tidal parameters. This paper outlines the main elements of the TEC itself, the environment it is located in and the measurement set up. In this paper, the flicker emitted by the TEC is compared with the different tidal parameters, including flood and ebb tides, tidal speed, water depth and turbulence strength and intensity. Flicker emissions have been calculated from measured data in over 90 measurement (10 min) periods, and all of the tidal parameters vary significantly over that testing period. This allows for a detailed statistical and graphical analysis of the variation of flicker with the variation of the tidal parameters outlined above. It is found, with the exception of tidal speed, that there is no strong relationship between flicker emissions and any other tidal parameter. As SeaGen is an asymmetrical TEC with full blade pitching for flood and ebb generation, it was also found that the expected difference of flicker emissions owing to the effect of the submersed crossbeam was not significant. The TEC harmonic performance versus tidal speed is also presented.

  18. 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. © 2013 Society for Conservation Biology No claim to original US government works.

  19. Semi-analytical solution of land-derived solute transport under tidal fluctuation in a confined aquifer

    Science.gov (United States)

    Suk, Heejun

    2017-11-01

    A one-dimensional semi-analytical solution of land-derived solute transport, subject to tidal fluctuation in a coastal confined aquifer, was derived using the generalized integral-transform technique (GITT). To investigate the plume migration of land-derived contaminants within a tidally influenced aquifer, both spatially and temporally varying expressions of the Darcy velocity and dispersion coefficients obtained from the analytical solution of the groundwater head response, which were subject to sinusoidal boundary conditions due to tidal fluctuation, were considered. This new semi-analytical solution was verified against a numerical solution, as well as the peak location trajectory obtained using the Predictor-Corrector method. Sensitivity analyses of tidal amplitude, hydraulic conductivity, and storage coefficient using the proposed solution were performed to understand plume behavior with regard to plume shape, plume spatial moments, and macrodispersion coefficients to gain a better understanding of the transport mechanisms. As the tidal amplitude, hydraulic conductivity, and storage coefficient were increased, the peaks were travelled faster, and peak concentrations were decreased. In addition, an increase in tidal amplitude, hydraulic conductivity, and storage coefficient caused an increase in variance as well as the macrodispersion coefficient. It was observed that negative macrodispersion appeared when the storage coefficient was largest, as well as when the difference between landward-directed advective velocity at the leading and trailing edges of the plume was greatest. This newly developed semi-analytical solution provides a useful mathematical tool for validating numerical models and understanding the physical mechanism of the migration of plume discharge to the sea or estuaries within a tidally influenced aquifer.

  20. 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

  1. Evaluation of ship-based sediment flux measurements by ADCPs in tidal flows

    Science.gov (United States)

    Becker, Marius; Maushake, Christian; Grünler, Steffen; Winter, Christian

    2017-04-01

    In the past decades acoustic backscatter calibration developed into a frequently applied technique to measure fluxes of suspended sediments in rivers and estuaries. Data is mainly acquired using single-frequency profiling devices, such as ADCPs. In this case, variations of acoustic particle properties may have a significant impact on the calibration with respect to suspended sediment concentration, but associated effects are rarely considered. Further challenges regarding flux determination arise from incomplete vertical and lateral coverage of the cross-section, and the small ratio of the residual transport to the tidal transport, depending on the tidal prism. We analyzed four sets of 13h cross-sectional ADCP data, collected at different locations in the range of the turbidity zone of the Weser estuary, North Sea, Germany. Vertical LISST, OBS and CTD measurements were taken very hour. During the calibration sediment absorption was taken into account. First, acoustic properties were estimated using LISST particle size distributions. Due to the tidal excursion and displacement of the turbidity zone, acoustic properties of particles changed during the tidal cycle, at all locations. Applying empirical functions, the lowest backscattering cross-section and highest sediment absorption coefficient were found in the center of the turbidity zone. Outside the tidally averaged location of the turbidity zone, changes of acoustic parameters were caused mainly by advection. In the turbidity zone, these properties were also affected by settling and entrainment, inducing vertical differences and systematic errors in concentration. In general, due to the iterative correction of sediment absorption along the acoustic path, local errors in concentration propagate and amplify exponentially. Based on reference concentration obtained from water samples and OBS data, we quantified these errors and their effect on cross-sectional averaged concentration and sediment flux. We found that

  2. Shelf sea tidal currents and mixing fronts determined from ocean glider observations

    Science.gov (United States)

    Sheehan, Peter M. F.; Berx, Barbara; Gallego, Alejandro; Hall, Rob A.; Heywood, Karen J.; Hughes, Sarah L.; Queste, Bastien Y.

    2018-03-01

    Tides and tidal mixing fronts are of fundamental importance to understanding shelf sea dynamics and ecosystems. Ocean gliders enable the observation of fronts and tide-dominated flows at high resolution. We use dive-average currents from a 2-month (12 October-2 December 2013) glider deployment along a zonal hydrographic section in the north-western North Sea to accurately determine M2 and S2 tidal velocities. The results of the glider-based method agree well with tidal velocities measured by current meters and with velocities extracted from the TPXO tide model. The method enhances the utility of gliders as an ocean-observing platform, particularly in regions where tide models are known to be limited. We then use the glider-derived tidal velocities to investigate tidal controls on the location of a front repeatedly observed by the glider. The front moves offshore at a rate of 0.51 km day-1. During the first part of the deployment (from mid-October until mid-November), results of a one-dimensional model suggest that the balance between surface heat fluxes and tidal stirring is the primary control on frontal location: as heat is lost to the atmosphere, full-depth mixing is able to occur in progressively deeper water. In the latter half of the deployment (mid-November to early December), a front controlled solely by heat fluxes and tidal stirring is not predicted to exist, yet a front persists in the observations. We analyse hydrographic observations collected by the glider to attribute the persistence of the front to the boundary between different water masses, in particular to the presence of cold, saline, Atlantic-origin water in the deeper portion of the section. We combine these results to propose that the front is a hybrid front: one controlled in summer by the local balance between heat fluxes and mixing and which in winter exists as the boundary between water masses advected to the north-western North Sea from diverse source regions. The glider observations

  3. Shelf sea tidal currents and mixing fronts determined from ocean glider observations

    Directory of Open Access Journals (Sweden)

    P. M. F. Sheehan

    2018-03-01

    Full Text Available Tides and tidal mixing fronts are of fundamental importance to understanding shelf sea dynamics and ecosystems. Ocean gliders enable the observation of fronts and tide-dominated flows at high resolution. We use dive-average currents from a 2-month (12 October–2 December 2013 glider deployment along a zonal hydrographic section in the north-western North Sea to accurately determine M2 and S2 tidal velocities. The results of the glider-based method agree well with tidal velocities measured by current meters and with velocities extracted from the TPXO tide model. The method enhances the utility of gliders as an ocean-observing platform, particularly in regions where tide models are known to be limited. We then use the glider-derived tidal velocities to investigate tidal controls on the location of a front repeatedly observed by the glider. The front moves offshore at a rate of 0.51 km day−1. During the first part of the deployment (from mid-October until mid-November, results of a one-dimensional model suggest that the balance between surface heat fluxes and tidal stirring is the primary control on frontal location: as heat is lost to the atmosphere, full-depth mixing is able to occur in progressively deeper water. In the latter half of the deployment (mid-November to early December, a front controlled solely by heat fluxes and tidal stirring is not predicted to exist, yet a front persists in the observations. We analyse hydrographic observations collected by the glider to attribute the persistence of the front to the boundary between different water masses, in particular to the presence of cold, saline, Atlantic-origin water in the deeper portion of the section. We combine these results to propose that the front is a hybrid front: one controlled in summer by the local balance between heat fluxes and mixing and which in winter exists as the boundary between water masses advected to the north-western North Sea from diverse source

  4. Diffusive Tidal Evolution for Migrating Hot Jupiters

    Science.gov (United States)

    Wu, Yanqin

    2018-03-01

    I consider a Jovian planet on a highly eccentric orbit around its host star, a situation produced by secular interactions with its planetary or stellar companions. The tidal interactions at every periastron passage exchange energy between the orbit and the planet’s degree-2 fundamental-mode. Starting from zero energy, the f-mode can diffusively grow to large amplitudes if its one-kick energy gain is ≥10‑5 of the orbital energy. This requires a pericenter distance of ≤4 tidal radii (or 1.6 Roche radii). If the f-mode has a non-negligible initial energy, diffusive evolution can occur at a lower threshold. The first effect can stall the secular migration as the f-mode can absorb orbital energy and decouple the planet from its secular perturbers, parking all migrating jupiters safely outside the zone of tidal disruption. The second effect leads to rapid orbit circularization as it allows an excited f-mode to continuously absorb orbital energy as the orbit eccentricity decreases. So without any explicit dissipation, other than the fact that the f-mode will damp nonlinearly when its amplitude reaches unity, the planet can be transported from a few au to ∼0.2 au in ∼104 years. Such a rapid circularization is equivalent to a dissipation factor Q ∼ 1, and it explains the observed deficit of super-eccentric Jovian planets. Lastly, the repeated f-mode breaking likely deposits energy and angular momentum in the outer envelope and avoids thermally ablating the planet. Overall, this work boosts the case for hot Jupiter formation through high-eccentricity secular migration.

  5. Stable channel of reclaimed tidal lowland

    Science.gov (United States)

    Syarifudin, Achmad; Imanuddin, Momon S.; Moerwanto, Arie S.; Suryadi, F. X.

    2017-11-01

    This study aimed to develop models of the Operation and Maintenance in the reclaimed tidal marsh area to get a stable channel. The research location is reclaimed tidal delta area Telang I Primary 8 representing land typology A/B and a survey conducted in 13 South Secondary Schemes following existing tertiary Telang I. MIKE - 11 computer models used used to analyze the movement of sediment in the channel in both the Primary channel 8, SPD, SDU and tertiary channels in block 13 South. Calibration model with multiple channels in the field of physical parameters has been performed to obtain results close to the results of measurement modeling sediment movement in the channel. The integration models of MIKE - 11 models with various scenarios are used to model the operation and maintenance of the channel in the tidal marsh area to get a stable channel. According to the scheme P8 - 13S, OM models obtained 75 percent, in which the secondary channel (SPD/SDU) and built flap gate in tertiary channel, get a well prototype model of the stable channel (equilibriums), where the average erosion on P8 at a distance of 3,200 m in the amount of 4,472,049 m3 and the mean sedimentation in the SPD of 963,836 m3 and mean of sedimentation in the tertiary channel of 3,508,213 m3. Similarly, on average erosion P8 by 4,135,649 m3 and the mean sedimentation in the SDU of 681,304 m3 and the mean sedimentation in the tertiary channel of 3,454,345 m3.

  6. Tidal Tales of Minor Mergers: Star Formation in the Tidal Tails of Minor Mergers

    Science.gov (United States)

    Knierman, Karen; Monkiewicz, Jacqueline; Scowen, Paul; Groppi, Christopher

    2018-01-01

    While major mergers and their tidal debris are well studied, equal mass galaxy mergers are relatively rare compared to minor mergers (mass ratio HI for 15 minor mergers, are providing a larger sample of environments to study the threshold for star formation that can inform star formation models, particularly at low densities.

  7. Physics and observations of tidal disruption events

    Science.gov (United States)

    Mangalam, Arun; Mageshwaran, Tamilan

    2018-04-01

    We describe a model of tidal disruption events (TDEs) with input physical parameters that include the black hole (BH) mass M•, the specific orbital energy E, the angular momentum J, the star mass M⊙ and radius R⊙. We calculate the rise time of the TDEs, the peak bolometric luminosity in terms of these physical parameters and a typical light curve of TDEs for various All Sky Survey (ASS) and Deep Sky Survey (DSS) missions. We then derive the expected detection rates and discuss the follow up of TDEs through observations in various spectral bands from X-rays to radio wavelengths.

  8. 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.

  9. 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

    NARCIS (Netherlands)

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

    2016-01-01

    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

  10. A new relativistic model for tidal stream evolution during tidal disruption events

    Science.gov (United States)

    Servin, Juan; Kesden, Michael

    2018-01-01

    When stars are tidally disrupted by a supermassive black hole, approximately half of their original mass becomes gravitationally bound and may eventually produce a tidal flare. The stellar debris evolves into streams that can self-intersect due to relativistic pericenter precession. Energy loss in these inelastic collisions both circularizes the stream and contributes to the tidal flare. Models of this process often assume that all elements of the tidal stream have the same specific energy and angular momentum as the most bound debris element. Real tidal debris possesses a distribution of binding energies, however, which grants it a distribution of orbits. We propose a new treatment for this debris, wherein we evolve the elements of the stream individually. We determine the radial distance (from the black hole) and the time (after the disruption) of the stream collisions as a function of black-hole mass under both Newtonian gravity (N+1PN) and general relativity (GR). We also use the Lane-Emden equation to account for the mass differences among the debris elements when calculating the energy loss in the inelastic collisions. For the N+1PN method, we evolve the stream using Newtonian orbital mechanics and apply pericenter precession after each pericenter passage using a first-order post-Newtonian approximation. Our relativistic method directly integrates the geodesic equations of motion. We see that the higher precession in the fully relativistic method results in more prompt collisions, and that assuming equal masses for the colliding debris elements greatly overestimates the energy loss resulting from these collisions. We also provide light curves for the corresponding flares and compare our predictions to those of previous models.

  11. 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.

  12. Observations of Tidal Straining Within Two Different Ocean Environments in the East China Sea: Stratification and Near-Bottom Turbulence

    Science.gov (United States)

    Yang, Wei; Wei, Hao; Zhao, Liang

    2017-11-01

    Tidal straining describes the straining effect induced by the vertical shear of oscillatory tidal currents that act on horizontal density gradients. It tends to create tidal periodic stratification and modulate the turbulence in the bottom boundary layer (BBL). Here, we present observations of current, hydrology and turbulence obtained at two mooring stations that are characterized by two typical hydrological environments in the East China Sea (ECS). One is located adjacent to the Changjiang River's mouth, and the other is located over a sloping shelf which is far from the freshwater sources. Tidal straining induces a semidiurnal switching between stable and unstable stratification at both stations. Near-bottom high-frequency velocity measurements further reveal that the dissipation rate of turbulent kinetic energy (TKE) is highly elevated during periods when unstable stratification occurs. A comparison between the TKE dissipation rate (ɛ) and the shear production (P) further reveals that the near-bottom mixing is locally shear-induced most of the time except during the unstable stratification period. Within this period, the magnitude of dissipation exceeds the expected value based on the law of the wall by an order of magnitude. The buoyancy flux that calculated by the balance method is too small to compensate for the existing discrepancy between the dissipation and shear production. Another plausible candidate is the advection of TKE, which may play an important role in the TKE budget during the unstable stratification period.

  13. Pond fractals in a tidal flat.

    Science.gov (United States)

    Cael, B B; Lambert, Bennett; Bisson, Kelsey

    2015-11-01

    Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during low tide of a tidal flat in Damariscotta, Maine, reveal a well-resolved power-law distribution of pond sizes over three orders of magnitude with a consistent fractal area-perimeter relationship. The data are consistent with the predictions of percolation theory for unscreened perimeters and scale-free cluster size distributions and are robust to alterations of the image processing procedure. The small spatial and temporal scales of these data suggest this easily observable system may serve as a useful model for investigating the evolution of pond geometries, while emphasizing the generality of fractal behavior in geophysical surfaces.

  14. 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”.

  15. 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.

  16. Time scales in tidal disruption events

    Directory of Open Access Journals (Sweden)

    Krolik J.

    2012-12-01

    Full Text Available We explore the temporal structure of tidal disruption events pointing out the corresponding transitions in the lightcurves of the thermal accretion disk and of the jet emerging from such events. The hydrodynamic time scale of the disrupted star is the minimal time scale of building up the accretion disk and the jet and it sets a limit on the rise time. This suggest that Swift J1644+57, that shows several flares with a rise time as short as a few hundred seconds could not have arisen from a tidal disruption of a main sequence star whose hydrodynamic time is a few hours. The disrupted object must have been a white dwarf. A second important time scale is the Eddington time in which the accretion rate changes form super to sub Eddington. It is possible that such a transition was observed in the light curve of Swift J2058+05. If correct this provides interesting constraints on the parameters of the system.

  17. Pond fractals in a tidal flat

    Science.gov (United States)

    Cael, B. B.; Lambert, Bennett; Bisson, Kelsey

    2015-11-01

    Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during low tide of a tidal flat in Damariscotta, Maine, reveal a well-resolved power-law distribution of pond sizes over three orders of magnitude with a consistent fractal area-perimeter relationship. The data are consistent with the predictions of percolation theory for unscreened perimeters and scale-free cluster size distributions and are robust to alterations of the image processing procedure. The small spatial and temporal scales of these data suggest this easily observable system may serve as a useful model for investigating the evolution of pond geometries, while emphasizing the generality of fractal behavior in geophysical surfaces.

  18. Heat-Induced, Pressure-Induced and Centrifugal-Force-Induced Exact Axisymmetric Thermo-Mechanical Analyses in a Thick-Walled Spherical Vessel, an Infinite Cylindrical Vessel, and a Uniform Disk Made of an Isotropic and Homogeneous Material

    Directory of Open Access Journals (Sweden)

    Vebil Yıldırım

    2017-07-01

    Full Text Available Heat-induced, pressure-induced, and centrifugal force-induced axisymmetric exact deformation and stresses in a thick-walled spherical vessel, a cylindrical vessel, and a uniform disk are all determined analytically at a specified constant surface temperature and at a constant angular velocity. The inner and outer pressures are both included in the formulation of annular structures made of an isotropic and homogeneous linear elastic material. Governing equations in the form of Euler-Cauchy differential equation with constant coefficients are solved and results are presented in compact forms. For disks, three different boundary conditions are taken into account to consider mechanical engineering applications. The present study is also peppered with numerical results in graphical forms.

  19. Nonlinear processes generated by supercritical tidal flow in shallow straits

    Science.gov (United States)

    Bordois, Lucie; Auclair, Francis; Paci, Alexandre; Dossmann, Yvan; Nguyen, Cyril

    2017-06-01

    Numerical experiments have been carried out using a nonhydrostatic and non-Boussinesq regional oceanic circulation model to investigate the nonlinear processes generated by supercritical tidal flow in shallow straits. Our approach relies on idealized direct numerical simulations inspired by oceanic observations. By analyzing a large set of simulations, a regime diagram is proposed for the nonlinear processes generated in the lee of these straits. The results show that the topography shape of the strait plays a crucial role in the formation of internal solitary waves (ISWs) and in the occurrence of local breaking events. Both of these nonlinear processes are important turbulence producing phenomena. The topographic control, observed in mode 1 ISW formation in previous studies [Y. Dossmann, F. Auclair, and A. Paci, "Topographically induced internal solitary waves in a pycnocline: Primary generation and topographic control," Phys. Fluids 25, 066601 (2013) and Y. Dossmann et al., "Topographically induced internal solitary waves in a pycnocline: Ultrasonic probes and stereo-correlation measurements," Phys. Fluids 26, 056601 (2014)], is clearly reproducible for mode-2 ISW above shallow straits. Strong plunging breaking events are observed above "narrow" straits (straits with a width less than mode 1 wavelength) when the fluid velocity exceeds the local mode 1 wave speed. These results are a step towards future works on vertical mixing quantification and localization around complex strait areas.

  20. 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... Tidal Canal. The draws of the Alameda County highway drawbridges at Park Street, mile 5.2; Fruitvale...

  1. Tidal power - a major prospect for the 21st century

    International Nuclear Information System (INIS)

    Haws, E.T.

    1997-01-01

    Tidal power technology is reviewed and its prospects for the next century assessed. It is concluded that the technology is now in place and, given the political will to secure financing, tidal power offers a clean, renewable and sustainable source of power for the near future. (UK)

  2. Relation between tidal damping and wave celerity in estuaries

    NARCIS (Netherlands)

    Savenije, H.H.G.; Veling, E.J.M.

    2005-01-01

    Observations in estuaries indicate that an amplified tidal wave moves considerably faster than is indicated by the classical equation for wave propagation. Similarly, the celerity of propagation is lower if the tidal wave is damped. This phenomenon is clearly observed in the Schelde estuary (located

  3. Potential sites for tidal power in New Jersey.

    Science.gov (United States)

    2014-04-01

    High-resolution simulation is made to model tidal energy along the coastlines of New Jersey (NJ) and its neighbor states with an : unprecedentedly fine grid. On the basis of the simulation, a thorough search is made for sites for tidal power generati...

  4. 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...

  5. Ammonium transformation in a nitrogen-rich tidal freshwater marsh

    DEFF Research Database (Denmark)

    Gribsholt, B.; Andersson, M.; Boschker, H.T.S.

    2006-01-01

    The fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nutrient rich Scheldt River, Belgium, was quantified in a whole ecosystem 15N labeling experiment. In late summer (September) we added 15N-NH4+ to the flood water entering a 3477 m2 tidal freshwater marsh...

  6. 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...

  7. 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

  8. Detecting areal changes in tidal flats after sea dike construction ...

    Indian Academy of Sciences (India)

    The area of tidal flats from a topographic map published in one year differs significantly from that shown in another, which appears to be attributable to the tide levels at the time of aerial photography. During the study period, the area of tidal flats, as estimated from Landsat-TM images, increased by 4.57 km2 per year in the ...

  9. Detecting areal changes in tidal flats after sea dike construction ...

    Indian Academy of Sciences (India)

    topographic map published in one year differs significantly from that shown in another, which appears to be attributable to the tide levels at the time of aerial photography. During the study period, the area of tidal flats, as estimated from Landsat-TM images, increased by 4.57 km. 2 per year in the study areas. The tidal flats in ...

  10. 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.

  11. 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.

  12. Tidal and gravity waves study from the airglow measurements at ...

    Indian Academy of Sciences (India)

    The other waves may be the upward propagating gravity waves or waves resulting from the interaction of inter-mode tidal oscillations, interaction of tidal waves with planetary waves and gravity waves. Some times, the second harmonic wave has higher vertical velocity than the corresponding fundamental wave. Application ...

  13. Wave and tidal generation devices reliability and availability

    CERN Document Server

    Tavner, Peter John

    2017-01-01

    To some extent the wave and tidal generation industry is following in the wake of the wind industry, learning from the growing experience of offshore wind farm deployment. This book combines wind industry lessons with wave and tidal field knowledge to explore the main reliability and availability issues facing this growing industry.

  14. 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...

  15. Forced tidal response in the Gulf of Mexico

    Science.gov (United States)

    Gouillon, Flavien; Morey, Steven L.; Dukhovskoy, Dmitry S.; O'Brien, James J.

    2010-10-01

    This study investigates the characteristics of tides in the Gulf of Mexico (GoM) and the response to forcing by local tidal potential and tides propagating as waves through straits connecting this semienclosed sea to the Caribbean Sea and Atlantic Ocean. Numerical simulations performed with the Navy Coastal Ocean Model run in a barotropic configuration with 1/60° horizontal resolution are used to analyze the tidal response to different forcing mechanisms. The tidal energy budget and tidal energy fluxes in the GoM are calculated from the simulations. Results show that diurnal tides in the GoM are dominantly due to co-oscillation with the western Atlantic and that a substantial amount of semidiurnal tidal energy also enters the Gulf through the straits. Model experiments suggest that adding the local tidal potential significantly modifies the propagation of the semidiurnal tidal signal within the GoM and reduces the tidal power associated with the diurnal tides in the basin. An interesting phenomenon of nonlinear interaction between the two forcing mechanisms (local forcing and propagation through the straits) is described and explained by using a mechanistic mass-spring system model.

  16. Detecting areal changes in tidal flats after sea dike construction ...

    Indian Academy of Sciences (India)

    The main objective of this study was to estimate changes in the area of tidal flats that occurred after sea dike construction on the western coast of South Korea using Landsat-TM images. Applying the ISODATA method of unsupervised classification for Landsat-TM images, the tidal flats were identified, and the resulting areas ...

  17. 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

  18. 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.

  19. Quantification of tidal inlet morphodynamics using high-resolution MBES and LiDAR

    DEFF Research Database (Denmark)

    Ernstsen, Verner Brandbyge; Lefebvre, Alice; Fraccascia, Serena

    the system is needed to assess the impact of potentially changing environmental conditions, such as accelerating sea level rise, increasing storm intensities and frequencies, or shifting wind directions. The aim of this study is to investigate the morphodynamics in a natural tidal inlet system, the Knudedyb......-bathymetric surveys using high-resolution red and green Light Detection And Ranging (LiDAR). Detailed digital elevation models with a grid cell size of 1 m x 1 m were generated and analysed geomorphometrically. The analyses reveal a main ebb-directed net sand transport in the main channel; however, due...

  20. A stand-alone tidal prediction application for mobile devices

    Science.gov (United States)

    Tsai, Cheng-Han; Fan, Ren-Ye; Yang, Yi-Chung

    2017-04-01

    It is essential for people conducting fishing, leisure, or research activities at the coasts to have timely and handy tidal information. Although tidal information can be found easily on the internet or using mobile device applications, this information is all applicable for only certain specific locations, not anywhere on the coast, and they need an internet connection. We have developed an application for Android devices, which allows the user to obtain hourly tidal height anywhere on the coast for the next 24 hours without having to have any internet connection. All the necessary information needed for the tidal height calculation is stored in the application. To develop this application, we first simulate tides in the Taiwan Sea using the hydrodynamic model (MIKE21 HD) developed by the DHI. The simulation domain covers the whole coast of Taiwan and the surrounding seas with a grid size of 1 km by 1 km. This grid size allows us to calculate tides with high spatial resolution. The boundary conditions for the simulation domain were obtained from the Tidal Model Driver of the Oregon State University, using its tidal constants of eight constituents: M2, S2, N2, K2, K1, O1, P1, and Q1. The simulation calculates tides for 183 days so that the tidal constants for the above eight constituents of each water grid can be extracted by harmonic analysis. Using the calculated tidal constants, we can predict the tides in each grid of our simulation domain, which is useful when one needs the tidal information for any location in the Taiwan Sea. However, for the mobile application, we only store the eight tidal constants for the water grids on the coast. Once the user activates the application, it reads the longitude and latitude from the GPS sensor in the mobile device and finds the nearest coastal grid which has our tidal constants. Then, the application calculates tidal height variation based on the harmonic analysis. The application also allows the user to input location and

  1. TIDAL STIRRING OF SATELLITES WITH SHALLOW DENSITY PROFILES PREVENTS THEM FROM BEING TOO BIG TO FAIL

    Energy Technology Data Exchange (ETDEWEB)

    Tomozeiu, Mihai; Mayer, Lucio [Institute for Computational Science, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Quinn, Thomas, E-mail: mihai@physik.uzh.ch [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195 (United States)

    2016-08-10

    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 ΛCDM “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 Milky Way (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 γ = 0.6 dark matter density distributions, as those resulting from the effect of feedback in hydrodynamical simulations of dwarf galaxy formation, are 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 adopted relation between the circular velocity at the half-light radius and the one-dimensional line of sight velocity dispersions are found. Such deviations are caused by the response of circular velocity profiles to tidal effects, which also varies depending on the initially assumed inner density profile and by the complexity of the stellar kinematics, which include residual rotation and anisotropy. In addition, tidal effects naturally induce large deviations in the stellar mass–halo mass relation for halo masses below 10{sup 9} M {sub ⊙}, preventing any reliable application of the abundance matching technique to dwarf galaxy satellites.

  2. nbody6tt: Tidal tensors in N-body simulations

    Science.gov (United States)

    Renaud, Florent

    2015-02-01

    nbody6tt, based on Aarseth's nbody6 (ascl:1102.006) code, includes the treatment of complex galactic tides in a direct N-body simulation of a star cluster through the use of tidal tensors (tt) and offers two complementary methods. The first allows consideration of any kind of galaxy and orbit, thus offering versatility; this method cannot be used to study tidal debris, as it relies on the tidal approximation (linearization of the tidal force). The second method is not limited by this and does not require a galaxy simulation; the user defines a numerical function which takes position and time as arguments, and the galactic potential is returned. The space and time derivatives of the potential are used to (i) integrate the motion of the cluster on its orbit in the galaxy (starting from user-defined initial position and velocity vector), and (ii) compute the tidal acceleration on the stars.

  3. 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

    The 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 non-tidal through oligohaline portion of two coastal plain rivers in Maryland, U.S.A., 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 one year period using artificial marker horizons, channel hydrology was measured over a one month period using acoustic Doppler current profilers, and SSC was predicted from acoustic backscatter. Riparian sediment accretion was lowest at the non-tidal 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 2-fold 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 non-tidal 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. Overall sediment accretion was higher in the embayed river likely due to a single storm discharge and associated sedimentation.

  4. NS begins tidal power test with 1 turbine

    International Nuclear Information System (INIS)

    Anon.

    2009-01-01

    The Bay of Fundy holds huge potential as a source of clean renewable tidal energy. This article announced the successful installation of a turbine that will test the potential of tidal power in the Bay of Fundy. Rather than requiring any dams or head ponds, new tidal power technologies include offshore floating tidal turbines and turbines that are anchored to the ocean floor to take advantage of natural tidal flows. In September 2009, Nova Scotia Power unveiled the 1 MW Open-Centre tidal turbine that was manufactured in Ireland by OpenHydro. The 10-metre turbine will be deployed in the Minas Passage as part of the Fundy Ocean Research Centre for Energy (FORCE) tidal test site. The turbine will rest directly on the ocean floor using a subsea gravity base made in Dartmouth by Cherubini Metal Works. It has several design features that minimize the impact on marine life. A large open centre provides a safe passage for marine life and the turbine's clean hydrodynamic lines ensure that fish will not become entangled. The use of oils, greases and other lubricants has also been avoided. The unit produces only very low levels of mechanical noise. A detailed turbine and environmental monitoring program will begin upon completion of the installation. Nova Scotia Power's involvement with the tidal energy test facility is supported by Sustainable Development Technology Canada. Nova Scotia Hydro owns and operates 1 of only 3 tidal power plants in the world, and the only one in the western hemisphere. The Annapolis Tidal Power plant, which came online in 1984, has a capacity of 20 MW and a daily output of about 80 to 100 megawatt hours.

  5. A improved tidal method without water level

    Science.gov (United States)

    Luo, xiaowen

    2017-04-01

    Now most tide are obtained use water Level and pressure type water gage, but it is difficult to install them and reading is in low accuracy in this method . In view of above-mentioned facts, In order to improve tide accuracy, A improved method is introduced.sea level is obtained in given time using high-precision GNSS buoy combined instantaneous position from pressure gage. two steps are as following, (1) the GNSS time service is used as the source of synchronization reference in tidal measurement; (2) centimeter-level sea surface positions are obtained in real time using difference GNSS The improved method used in seafloor topography survey,in 145 cross points, 95% meet the requirements of the Hydrographic survey specification. It is effective method to obtain higher accuracy tide.

  6. Dwarf Galaxies Swimming in Tidal Tails

    Science.gov (United States)

    2005-01-01

    This false-color infrared image from NASA's Spitzer Space Telescope shows little 'dwarf galaxies' forming in the 'tails' of two larger galaxies that are colliding together. The big galaxies are at the center of the picture, while the dwarfs can be seen as red dots in the red streamers, or tidal tails. The two blue dots above the big galaxies are stars in the foreground. Galaxy mergers are common occurrences in the universe; for example, our own Milky Way galaxy will eventually smash into the nearby Andromeda galaxy. When two galaxies meet, they tend to rip each other apart, leaving a trail, called a tidal tail, of gas and dust in their wake. It is out of this galactic debris that new dwarf galaxies are born. The new Spitzer picture demonstrates that these particular dwarfs are actively forming stars. The red color indicates the presence of dust produced in star-forming regions, including organic molecules called polycyclic aromatic hydrocarbons. These carbon-containing molecules are also found on Earth, in car exhaust and on burnt toast, among other places. Here, the molecules are being heated up by the young stars, and, as a result, shine in infrared light. This image was taken by the infrared array camera on Spitzer. It is a 4-color composite of infrared light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). Starlight has been subtracted from the orange and red channels in order to enhance the dust features.

  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. TIDALLY DRIVEN DYNAMOS IN A ROTATING SPHERE

    International Nuclear Information System (INIS)

    Cébron, D.; Hollerbach, R.

    2014-01-01

    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

  9. 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.

  10. Longitudinal variation in lateral trapping of fine sediment in tidal estuaries: observations and a 3D exploratory model

    Science.gov (United States)

    Chen, Wei; de Swart, Huib E.

    2018-03-01

    This study investigates the longitudinal variation of lateral entrapment of suspended sediment, as is observed in some tidal estuaries. In particular, field data from the Yangtze Estuary are analysed, which reveal that in one cross-section, two maxima of suspended sediment concentration (SSC) occur close to the south and north sides, while in a cross-section 2 km down-estuary, only one SSC maximum on the south side is present. This pattern is found during both spring tide and neap tide, which are characterised by different intensities of turbulence. To understand longitudinal variation in lateral trapping of sediment, results of a new three-dimensional exploratory model are analysed. The hydrodynamic part contains residual flow due to fresh water input, density gradients and Coriolis force and due to channel curvature-induced leakage. Moreover, the model includes a spatially varying eddy viscosity that accounts for variation of intensity of turbulence over the spring-neap cycle. By imposing morphodynamic equilibrium, the two-dimensional distribution of sediment in the domain is obtained analytically by a novel procedure. Results reveal that the occurrence of the SSC maxima near the south side of both cross-sections is due to sediment entrapment by lateral density gradients, while the second SSC maximum near the north side of the first cross-section is by sediment transport due to curvature-induced leakage. Coriolis deflection of longitudinal flow also contributes the trapping of sediment near the north side. This mechanism is important in the upper estuary, where the flow due to lateral density gradients is weak.

  11. Characterisation of Tidal Flows at the European Marine Energy Centre in the Absence of Ocean Waves

    Directory of Open Access Journals (Sweden)

    Brian G. Sellar

    2018-01-01

    Full Text Available The data analyses and results presented here are based on the field measurement campaign of the Reliable Data Acquisition Platform for Tidal (ReDAPT project (Energy Technologies Institute (ETI, U.K. 2010–2015. During ReDAPT, a 1 MW commercial prototype tidal turbine was deployed and operated at the Fall of Warness tidal test site within the European Marine Energy Centre (EMEC, Orkney, U.K. Mean flow speeds and Turbulence Intensity (TI at multiple positions proximal to the machine are considered. Through the implemented wave identification techniques, the dataset can be filtered into conditions where the effects of waves are present or absent. Due to the volume of results, only flow conditions in the absence of waves are reported here. The analysis shows that TI and mean flows are found to vary considerably between flood and ebb tides whilst exhibiting sensitivity to the tidal phase and to the specification of spatial averaging and velocity binning. The principal measurement technique was acoustic Doppler profiling provided by seabed-mounted Diverging-beam Acoustic Doppler Profilers (D-ADP together with remotely-operable Single-Beam Acoustic Doppler Profilers (SB-ADP installed at mid-depth on the tidal turbine. This novel configuration allows inter-instrument comparisons, which were conducted. Turbulence intensity averaged over the rotor extents of the ReDAPT turbine for flood tides vary between 16.7% at flow speeds above 0.3 m/s and 11.7% when considering only flow speeds in the turbine operating speed range, which reduces to 10.9% (6.8% relative reduction following the implementation of noise correction techniques. Equivalent values for ebb tides are 14.7%, 10.1% and 9.3% (7.9% relative reduction. For flood and ebb tides, TI values resulting from noise correction are reduced in absolute terms by 3% and 2% respectively across a wide velocity range and approximately 1% for turbine operating speeds. Through comparison with SB-ADP-derived mid

  12. Device interactions in reducing the cost of tidal stream energy

    International Nuclear Information System (INIS)

    Vazquez, A.; Iglesias, G.

    2015-01-01

    Highlights: • Numerical modelling is used to estimate the levelised cost of tidal stream energy. • As a case study, a model of Lynmouth (UK) is implemented and successfully validated. • The resolution of the model allows the demarcation of individual devices on the model grid. • Device interactions reduce the available tidal resource and the cost increases significantly. - Abstract: The levelised cost of energy takes into account the lifetime generated energy and the costs associated with a project. The objective of this work is to investigate the effects of device interactions on the energy output and, therefore, on the levelised cost of energy of a tidal stream project, by means of numerical modelling. For this purpose, a case study is considered: Lynmouth (North Devon, UK), an area in the Bristol Channel in which the first tidal stream turbine was installed − a testimony of its potential as a tidal energy site. A state-of-the-art hydrodynamics model is implemented on a high-resolution computational grid, which allows the demarcation of the individual devices. The modification to the energy output resulting from interaction between turbines within the tidal farm is thus resolved for each individual turbine. The results indicate that significant changes in the levelised cost of energy values, of up to £0.221 kW h −1 , occur due to the aforementioned modifications, which should not be disregarded if the cost of tidal stream energy is to be minimised

  13. [Characteristics of tidal breathing pulmonary function in children with tracheobronchomalacia].

    Science.gov (United States)

    Li, Lan; Chen, Qaing; Zhang, Fan; Zhu, Shuang-Gui; Hu, Ci-Lang; Wu, Ai-Min

    2017-12-01

    To investigate the characteristics of tidal breathing pulmonary function in children with tracheobronchomalacia (TBM). In this study, 30 children who were diagnosed with TBM using electronic bronchoscopy were enrolled in the observation group; 30 healthy children were recruited in the normal control group. For individuals in each group, the assessment of tidal breath pulmonary function was performed at diagnosis and 3, 6, 9, and 12 months after diagnosis. There were no significant differences in tidal volume, inspiratory time, expiratory time, and inspiratory to expiratory ratio between the two groups (P>0.05). Compared with the control group, the observation group had a significantly higher respiratory rate and significantly lower ratio of time to peak tidal expiratory flow to total expiratory time (TPTEF/TE) and ratio of volume to peak tidal expiratory flow to total expiratory volume (VPTEF/VE). There was a time-dependent increase in TPTEF/TE and VPTEF/VE for TBM children from the time of initial diagnosis to 12 months after diagnosis. Tidal breathing pulmonary function has characteristic changes in children with TBM. Tidal breathing pulmonary function tends to be recovered with increased age in children with TBM.

  14. Large tidal plants may supply 1,000 TWh / year

    International Nuclear Information System (INIS)

    Lemperiere, F.

    2006-10-01

    Many studies of tidal plants have been made fifty years ago: they were usually devoted to sites with average tidal head over 6 m and reduced works at sea: estuaries such as La Rance (France) or Severn (U.K.) were favoured: preferred corresponding operation was using flow from a high basin to low sea level, supplying power 4 hours from 12. Such solutions had 2 drawbacks: power supply poorly adapted to needs and modified shore tidal ecosystems. Beyond that the power cost was usually higher than from thermal plants and very few plants were built, the main one being the Rance plant in France supplying 0,5 TWh/year with 240 MW. The world theoretical tidal potential is in the same range as the traditional hydropower potential. A new approach of tidal plants based upon solutions existing now and using new operating methods substantiates the possibility of over 1,000 TWh/year of cost efficient tidal energy with limited environmental impact and power supply well adapted to requirements. Over 15 countries may be involved. Tidal plants with heads as low as 4 m may be cost efficient. (author)

  15. The ocean response at multiple space and time scales to tidal stream energy extraction by a large-scale turbine array.

    Science.gov (United States)

    De Dominicis, Michela; O'Hara Murray, Rory; Wolf, Judith

    2017-04-01

    A comprehensive assessment of the tidal energy resource realistically available for electricity generation and the study of the potential environmental impacts associated with its extraction in the Pentland Firth (Scottish Waters, UK) are presented. In order to examine both local (100 km) spatial scales, the Scottish Shelf Model (SSM), an unstructured grid three-dimensional FVCOM (Finite Volume Community Ocean Model) model implementation has been used, since it covers the entire NW European Shelf, with a high resolution where the tidal stream energy is extracted. A large theoretical array of tidal stream turbines has been designed and implemented in the model using the momentum sink approach, in which a momentum sink term represents the loss of momentum due to tidal energy extraction. The estimate of the maximum available power for electricity generation from the Pentland Firth is 1.64 GW, which requires thousands of turbines to be deployed. This estimate takes into account the tidal stream energy extraction feedbacks on the flow and considers, for the first time, the realistic operation of a generic tidal stream turbine, which is limited to operate in a range of flow velocities due to technological constraints. The ocean response to the extraction of 1.64 GW of energy has been examined by comparing a typical annual cycle of the NW European Shelf hydrodynamics reproduced by the SSM with the same period perturbed by tidal stream energy extraction. The changes were analysed at the temporal scale of a spring-neap tidal cycle and, for the first time, on longer term seasonal timescales. Tidal elevation mainly increases in the vicinity of the tidal farm, while far-field effects show a decrease in the mean spring tidal range of the order of 2 cm along the whole east coast of the UK, possibly counteracting some part of the predicted sea level rise due to climate change. Marine currents, both tidal and residual flows, are also affected. They can slow down due to the

  16. Tidal day organic and inorganic material flux of ponds in the Liberty Island freshwater tidal wetland.

    Science.gov (United States)

    Lehman, Peggy W; Mayr, Shawn; Liu, Leji; Tang, Alison

    2015-01-01

    The loss of inorganic and organic material export and habitat produced by freshwater tidal wetlands is hypothesized to be an important contributing factor to the long-term decline in fishery production in San Francisco Estuary. However, due to the absence of freshwater tidal wetlands in the estuary, there is little information on the export of inorganic and organic carbon, nutrient or phytoplankton community biomass and the associated mechanisms. A single-day study was conducted to assess the potential contribution of two small vegetated ponds and one large open-water pond to the inorganic and organic material flux within the freshwater tidal wetland Liberty Island in San Francisco Estuary. The study consisted of an intensive tidal day (25.5 h) sampling program that measured the flux of inorganic and organic material at three ponds using continuous monitoring of flow, chlorophyll a, turbidity and salt combined with discrete measurements of phytoplankton community carbon, total and dissolved organic carbon and nutrient concentration at 1.5 h intervals. Vegetated ponds had greater material concentrations than the open water pond and, despite their small area, contributed up to 81% of the organic and 61% of the inorganic material flux of the wetland. Exchange between ponds was important to wetland flux. The small vegetated pond in the interior of the wetland contributed as much as 72-87% of the total organic carbon and chlorophyll a and 10% of the diatom flux of the wetland. Export of inorganic and organic material from the small vegetated ponds was facilitated by small-scale topography and tidal asymmetry that produced a 40% greater material export on ebb tide. The small vegetated ponds contrasted with the large open water pond, which imported 29-96% of the inorganic and 4-81% of the organic material into the wetland from the adjacent river. This study identified small vegetated ponds as an important source of inorganic and organic material to the wetland and the

  17. 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.

  18. Cyclic PaO2 oscillations assessed in the renal microcirculation: correlation with tidal volume in a porcine model of lung lavage.

    Science.gov (United States)

    Thomas, Rainer; Möllmann, Christian; Ziebart, Alexander; Liu, Tanghua; David, Matthias; Hartmann, Erik K

    2017-07-11

    Oscillations of the arterial partial pressure of oxygen induced by varying shunt fractions occur during cyclic alveolar recruitment within the injured lung. Recently, these were proposed as a pathomechanism that may be relevant for remote organ injury following acute respiratory distress syndrome. This study examines the transmission of oxygen oscillations to the renal tissue and their tidal volume dependency. Lung injury was induced by repetitive bronchoalveolar lavage in eight anaesthetized pigs. Cyclic alveolar recruitment was provoked by high tidal volume ventilation. Oscillations of the arterial partial pressure of oxygen were measured in real-time in the macrocirculation by multi-frequency phase fluorimetry and in the renal microcirculation by combined white-light spectrometry and laser-Doppler flowmetry during tidal volume down-titration. Significant respiratory-dependent oxygen oscillations were detected in the macrocirculation and transmitted to the renal microcirculation in a substantial extent. The amplitudes of these oscillations significantly correlate to the applied tidal volume and are minimized during down-titration. In a porcine model oscillations of the arterial partial pressure of oxygen are induced by cyclic alveolar recruitment and transmitted to the renal microcirculation in a tidal volume-dependent fashion. They might play a role in organ crosstalk and remote organ damage following lung injury.

  19. 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

  20. Bars and spirals in tidal interactions with an ensemble of galaxy mass models

    Science.gov (United States)

    Pettitt, Alex R.; Wadsley, J. W.

    2018-03-01

    We present simulations of the gaseous and stellar material in several different galaxy mass models under the influence of different tidal fly-bys to assess the changes in their bar and spiral morphology. Five different mass models are chosen to represent the variety of rotation curves seen in nature. We find a multitude of different spiral and bar structures can be created, with their properties dependent on the strength of the interaction. We calculate pattern speeds, spiral wind-up rates, bar lengths, and angular momentum exchange to quantify the changes in disc morphology in each scenario. The wind-up rates of the tidal spirals follow the 2:1 resonance very closely for the flat and dark matter-dominated rotation curves, whereas the more baryon-dominated curves tend to wind-up faster, influenced by their inner bars. Clear spurs are seen in most of the tidal spirals, most noticeable in the flat rotation curve models. Bars formed both in isolation and interactions agree well with those seen in real galaxies, with a mixture of `fast' and `slow' rotators. We find no strong correlation between bar length or pattern speed and the interaction strength. Bar formation is, however, accelerated/induced in four out of five of our models. We close by briefly comparing the morphology of our models to real galaxies, easily finding analogues for nearly all simulations presenter here, showing passages of small companions can easily reproduce an ensemble of observed morphologies.

  1. 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.

  2. Avian response to tidal freshwater habitat creation by controlled reduced tide system

    Science.gov (United States)

    Beauchard, Olivier; Jacobs, Sander; Ysebaert, Tom; Meire, Patrick

    2013-10-01

    Human activities have caused extensive loss of estuarine wetlands, and the restoration of functional habitats remains a challenging task given several physical constraints in strongly embanked estuaries. In the Schelde estuary (Belgium), a new tidal marsh restoration technique, Controlled Reduced Tide system (CRT), is being implemented in the freshwater zone. A polder area of 8.2 ha was equipped with a CRT to test the system functionality. Among different ecological compartments that are studied for assessing the CRT restoration success, avifauna was monitored over three years. The tidal regime generated a habitat gradient typical of tidal freshwater wetlands along which the distributions of bird and ecological groups were studied. 103 bird species were recorded over the three years. In addition to many generalist bird species, several specialist species typical of the North Sea coast were present. Thirty-nine species of local and/or international conservation interest were encountered, emphasising the importance of this habitat for certain species. Species communities and ecological groups were strongly habitat specific and non-randomly organized across habitats. Spatiotemporal analyses highlighted a rapid habitat colonization, and a subsequent stable habitat community structure across seasons in spite of strong seasonal species turnovers. Hence, these findings advocate CRT implementation as a means to effectively compensate for wetland habitat loss.

  3. Sedimentation rate and lateral migration of tidal channels in the Lagoon of Venice (Northern Italy)

    Science.gov (United States)

    Donnici, Sandra; Madricardo, Fantina; Serandrei-Barbero, Rossana

    2017-11-01

    Tidal channels are crucial for the functioning of highly valuable coastal environments, such as estuaries and lagoons. Their properties, however, are currently less understood than those of river systems. To elucidate their past behaviour, an extensive geophysical investigation was performed to reconstruct the evolution of channels and tidal surfaces in the central part of the Lagoon of Venice (Italy) over the past 5000 years. Comparing high-spatial-resolution acoustic data and sedimentary facies analyses of 41 cores, 29 of which were radiocarbon dated, revealed the sedimentation rates in different lagoonal environments and allowed the migration of two large meanders to be reconstructed. The average sedimentation rate of the study succession in the different sedimentary environments was 1.27 mm yr-1. The lateral migration rates were 13-23 m/century. This estimate is consistent with the lateral migration rates determined by comparing aerial photographs of recent channels. Comparing the buried channels with historical and current maps showed that, in general, the number of active channels is now reduced. Their morphology was sometimes simplified by artificial interventions. An understanding of the impact of the artificial interventions over time is useful for the management and conservation of tidal environments, particularly for the Lagoon of Venice, where management authorities are currently debating the possible deepening and rectification of large navigation channels.

  4. Monitoring of end tidal carbon dioxide and transcutaneous carbon dioxide during neonatal transport.

    Science.gov (United States)

    Tingay, D G; Stewart, M J; Morley, C J

    2005-11-01

    To assess the accuracy of measurements of end tidal carbon dioxide (CO2) during neonatal transport compared with arterial and transcutaneous measurements. Paired end tidal and transcutaneous CO2 recordings were taken frequently during road transport of 21 ventilated neonates. The first paired CO2 values were compared with an arterial blood gas. The differences between arterial CO2 (Paco2), transcutaneous CO2 (TcPco2), and end tidal CO2 (Petco2) were analysed. The Bland-Altman method was used to assess bias and repeatability. Petco2 correlated strongly with Paco2 and TcPco2. However, Petco2 underestimated Paco2 at a clinically unacceptable level (mean (SD) 1.1 (0.70) kPa) and did not trend reliably over time within individual subjects. The Petco2 bias was independent of Paco2 and severity of lung disease. Petco2 had an unacceptable under-recording bias. TcPco2 should currently be considered the preferred method of non-invasive CO2 monitoring for neonatal transport.

  5. Financial and environmental costs of manual versus automated control of end-tidal gas concentrations.

    Science.gov (United States)

    Tay, S; Weinberg, L; Peyton, P; Story, D; Briedis, J

    2013-01-01

    Emerging technologies that reduce the economic and environmental costs of anaesthesia have had limited assessment. We hypothesised that automated control of end-tidal gases, a new feature in anaesthesia machines, will consistently reduce volatile agent consumption cost and greenhouse gas emissions. As part of the planned replacement of anaesthesia machines in a tertiary hospital, we performed a prospective before and after study comparing the cost and greenhouse gas emissions of isoflurane, sevoflurane and desflurane when using manual versus automated control of end-tidal gases. We analysed 3675 general anaesthesia cases with inhalational agents: 1865 using manual control and 1810 using automated control. Volatile agent cost was $18.87/hour using manual control and $13.82/hour using automated control: mean decrease $5.05/hour (95% confidence interval: $0.88-9.22/hour, P=0.0243). The 100-year global warming potential decreased from 23.2 kg/hour of carbon dioxide equivalents to 13.0 kg/hour: mean decrease 10.2 kg/hour (95% confidence interval: 2.7-17.7 kg/hour, P=0.0179). Automated control reduced costs by 27%. Greenhouse gas emissions decreased by 44%, a greater than expected decrease facilitated by a proportional reduction in desflurane use. Automated control of end-tidal gases increases participation in low flow anaesthesia with economic and environmental benefits.

  6. Coupling of sea level and tidal range changes, with implications for future water levels.

    Science.gov (United States)

    Devlin, Adam T; Jay, David A; Talke, Stefan A; Zaron, Edward D; Pan, Jiayi; Lin, Hui

    2017-12-05

    Are perturbations to ocean tides correlated with changing sea-level and climate, and how will this affect high water levels? Here, we survey 152 tide gauges in the Pacific Ocean and South China Sea and statistically evaluate how the sum of the four largest tidal constituents, a proxy for the highest astronomical tide (HAT), changes over seasonal and interannual time scales. We find that the variability in HAT is significantly correlated with sea-level variability; approximately 35% of stations exhibit a greater than ±50 mm tidal change per meter sea-level fluctuation. Focusing on a subset of three stations with long records, probability density function (PDF) analyses of the 95% percentile exceedance of total sea level (TSL) show long-term changes of this high-water metric. At Hong Kong, the increase in tides significantly amplifies the risk caused by sea-level rise. Regions of tidal decrease and/or amplification highlight the non-linear response to sea-level variations, with the potential to amplify or mitigate against the increased flood risk caused by sea-level rise. Overall, our analysis suggests that in many regions, local flood level determinations should consider the joint effects of non-stationary tides and mean sea level (MSL) at multiple time scales.

  7. 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

    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...

  8. 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...

  9. Bedload transport in an inlet channel during a tidal cycle

    DEFF Research Database (Denmark)

    Ernstsen, V. B.; Becker, M.; Winter, C.

    2007-01-01

      Based on high-resolution swath bathymetry measurements at centimetre-scale precision conducted during a tidal cycle in a dune field in the Grådyb tidal inlet channel in the DanishWadden Sea, a simple tool to calculate bedload transport is presented. Bedload transport was related to simultaneous...... dunes being active during the ebb tide, but negligible during the flood tide. Bedload transport was also predicted using five classical and widely used formulae. These predictors were all unable to depict the temporal variation in bedload transport during the tidal cycle. It is suggested that temporal...

  10. Stability of Circular Orbits around a Tidal Charged Black Hole

    Science.gov (United States)

    Sharif, M.; Kousar, L.

    2018-01-01

    We study the effects of the tidal charge on the equatorial circular motion of neutral test particles near a tidal charged black hole. This analysis investigates stable as well as unstable circular orbits in all possible configurations of nonextremal and extremal cases. It is found that a negative tidal charge will increase the energy and angular momentum of a neutral test particle moving around a black hole. We obtain a continuous region of stability for both extremal and nonextremal cases. We conclude that the region of stability as well as radius of last stable circular orbit shows increasing behavior for Q < 0.

  11. Tidal energy UK Government R and D programme. Final report

    International Nuclear Information System (INIS)

    Craig, J.W.; Davies, L.M.; Allington, M.A.

    1996-05-01

    The United Kingdom Government's research programme into the feasibility of exploiting tidal power for electricity generation in Britain's estuaries is described in this document. The history of the research is included from the Severn Barrage Committee in 1978 to the conclusion of the tidal energy barrages programme in 1994. The programme sought to reduce uncertainty on costs, technical performance and environmental and regional effects, in order to firm up on decisions on whether to construct certain specific barrages. It was concluded that, while technically feasible, tidal power from barrages, was and will continue to be uneconomic compared with other energy sources. Other renewable technologies would receive further research. (UK)

  12. The dependence of galaxy clustering on tidal environment in the Sloan Digital Sky Survey

    Science.gov (United States)

    Paranjape, Aseem; Hahn, Oliver; Sheth, Ravi K.

    2018-03-01

    The influence of the Cosmic Web on galaxy formation and evolution is of great observational and theoretical interest. We investigate whether the Cosmic Web leaves an imprint in the spatial clustering of galaxies in the Sloan Digital Sky Survey (SDSS), using the group catalog of Yang et al. and tidal field estimates at ˜2h-1Mpc scales from the Mass-Tides-Velocity data set of Wang et al. We use the tidal anisotropy α (Paranjape et al.) to characterise the tidal environment of groups, and measure the redshift-space 2-point correlation function (2pcf) of group positions and the luminosity- and colour-dependent clustering of group galaxies using samples segregated by α. We find that all the 2pcf measurements depend strongly on α, with factors of ˜20 between the large-scale 2pcf of objects in the most and least isotropic environments. To test whether these strong trends imply `beyond halo mass' effects for galaxy evolution, we compare our results with corresponding 2pcf measurements in mock catalogs constructed using a halo occupation distribution that only uses halo mass as an input. We find that this prescription qualitatively reproduces all observed trends, and also quantitatively matches many of the observed results. Although there are some statistically significant differences between our `halo mass only' mocks and the data - in the most and least isotropic environments - which deserve further investigation, our results suggest that if the tidal environment induces additional effects on galaxy properties other than those inherited from their host haloes, then these must be weak.

  13. Salt Marsh Ecosystem Responses to Restored Tidal Connectivity across a 14y Chronosequence

    Science.gov (United States)

    Capooci, M.; Spivak, A. C.; Gosselin, K.

    2016-02-01

    Salt marshes support valuable ecosystem services. Yet, human activities negatively impact salt marsh function and contribute to their loss at a global scale. On Cape Cod, MA, culverts and impoundments under roads and railways restricted tidal exchange and resulted in salt marsh conversion to freshwater wetlands. Over the past 14 y, these structures have been removed or replaced, restoring tidal connectivity between marshes and a saltwater bay. We evaluated differences in plant community composition, sediment properties, and pore water chemistry in marshes where tidal connectivity was restored using a space-for-time, or chronosequence approach. Each restored marsh was paired with a nearby, natural salt marsh to control for variability between marshes. In each restored and natural salt marsh we evaluated the plant community by measuring species-specific percent cover and biomass and collected sediment cores for bulk density and pore water analyses. Plant communities responded rapidly: salt-tolerant species, such as Spartina alterniflora, became established while freshwater species, including Phragmites australis, were less abundant within 3 y of restoration. The number of plant species was generally greater in marshes restored within 10 y, compared to older and natural marshes. Sediment bulk density varied with depth and across sites. This likely reflects differences in site history and local conditions. Deeper horizons (24-30cm) generally had higher values in restored sites while surface values (0-3cm) were similar in restored and natural marshes. Porewater pH and sulfide were similar in restored and natural marshes, suggesting rapid microbial responses to seawater reintroduction. Overall, marsh properties and processes reflecting biological communities responded rapidly to tidal restoration. However, variability between study locations underscores the potential importance of site history, local hydrology, and geomorphology in shaping marsh biogeochemistry.

  14. 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

  15. Depth-averaged instantaneous currents in a tidally dominated shelf sea from glider observations

    Science.gov (United States)

    Merckelbach, Lucas

    2016-12-01

    Ocean gliders have become ubiquitous observation platforms in the ocean in recent years. They are also increasingly used in coastal environments. The coastal observatory system COSYNA has pioneered the use of gliders in the North Sea, a shallow tidally energetic shelf sea. For operational reasons, the gliders operated in the North Sea are programmed to resurface every 3-5 h. The glider's dead-reckoning algorithm yields depth-averaged currents, averaged in time over each subsurface interval. Under operational conditions these averaged currents are a poor approximation of the instantaneous tidal current. In this work an algorithm is developed that estimates the instantaneous current (tidal and residual) from glider observations only. The algorithm uses a first-order Butterworth low pass filter to estimate the residual current component, and a Kalman filter based on the linear shallow water equations for the tidal component. A comparison of data from a glider experiment with current data from an acoustic Doppler current profilers deployed nearby shows that the standard deviations for the east and north current components are better than 7 cm s-1 in near-real-time mode and improve to better than 6 cm s-1 in delayed mode, where the filters can be run forward and backward. In the near-real-time mode the algorithm provides estimates of the currents that the glider is expected to encounter during its next few dives. Combined with a behavioural and dynamic model of the glider, this yields predicted trajectories, the information of which is incorporated in warning messages issued to ships by the (German) authorities. In delayed mode the algorithm produces useful estimates of the depth-averaged currents, which can be used in (process-based) analyses in case no other source of measured current information is available.

  16. 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.

  17. 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.

  18. Control of plant leaf movements by the lunisolar tidal force.

    Science.gov (United States)

    Fisahn, Joachim

    2018-01-24

    Investigations into the diurnal ascent and descent of leaves of beans and other species, as well as experimental interventions into these movements, such as exposures to light at different times during the movement cycle, led to the concept of an endogenous 'clock' as a regulator of these oscillations. The causal origin of leaf movement can be traced to processes that modulate cell volume in target tissues of the pulvinus and petiole. However, these elements of the leaf-movement process do not sufficiently account for the rhythms that are generated following germination in constant light or dark conditions, or when plants are transferred to similar free-running conditions. To further unravel the regulation of leaf-movement rhythms, many of the published time courses of leaf movements that provided evidence for the concept of the endogenous clock were analysed in conjunction with the contemporaneous time courses of the lunisolar tidal acceleration. This was accomplished by application of the Etide program, which estimates, with high temporal resolution, local gravitational changes as a consequence of the diurnal variations of the lunisolar gravitational force due to the orbits and relative positions of Earth, Moon and Sun. To substantiate the results obtained in earthbound laboratories additional experiments were performed in the International Space Station (ISS). Tidal recurrence within the ISS exhibited a periodicity of 45 min. In all instances investigated, it was evident that a synchronism exists between the times of the turning points of both the lunisolar tide and of the leaftide when the direction of leaf movement changes. This finding of synchrony documents that the lunisolar tide is a regulator of the leaftide, and that the rhythm of leaf movement is not of endogenous origin but is an expression of an exogenous lunisolar clock impressed upon the leaf-movement apparatus. A huge number of correlations between leaftide and Etide time courses were established

  19. Linking freshwater tidal hydrology to carbon cycling in bottomland hardwood wetlands

    Science.gov (United States)

    Carl C. Trettin; Brooke J. Czwartacki; Craig J. Allan; Devendra M. Amatya

    2016-01-01

    Hydrology is recognized as one of the principal factors regulating soil biogeochemical processes in forested wetlands. However, the consequences of tidally mediated hydrology are seldom considered within forested wetlands that occur along tidal water bodies. These tidal water bodies may be either fresh or brackish, and the tidal streams function as a reservoir to...

  20. Formation and early evolution of narrow planetary rings following the tidal disruption of satellites

    Science.gov (United States)

    Ogilvie, G. I.; Leinhardt, Z. M.; Latter, H. N.; Kokubo, E.

    2012-09-01

    Satellites that are formed inside the corotation radius of a planet migrate slowly inwards as a result of tidal dissipation in the central body. Eventually they are tidally disrupted and form planetary rings. We use N-body simulations of gravitational aggregates (rubble piles) to study the tidal disruption of both homogeneous satellites and differentiated bodies containing a denser core. These bodies are initially placed in synchronous rotation on circular orbits at different distances from the planet. In cases where tidal disruption occurs, we analyse the disruption process and the properties of the rings that are formed. We find that the Roche limit for a rubble pile is closer to the planet than for a fluid body of the same mean density, and this effect is enhanced if the satellite is differentiated. Significant zones exist around Uranus and Neptune in which inward migration and tidal disruption may occur; similar zones may have existed around the early Jupiter and Saturn. Within its Roche limit, a homogeneous satellite is totally disrupted and forms a narrow ring. The initial stages of the disruption are similar to the evolution of a viscous fluid ellipsoid, which can be computed semianalytically. Later, however, gravitational instability produces irregular structure and dynamics within the ring. On the other hand, a differentiated satellite tends to undergo a disruption of its mantle only. This process is similar to Roche-lobe overflow in interacting binary stars, although proceeding simultaneously through both Lagrange points L1 and L2, and produces streams of ejected particles whose trajectories are initially well described by solutions of the restricted three-body problem. Again, however, gravitational instability affects the streams near nodes where the particles comes almost to rest in the corotating frame and the density is enhanced. This type of disruption process produces two narrow rings on either side of a remnant satellite. If a differentiated

  1. Sears Point Tidal Marsh Restoration Project: Phase I

    Science.gov (United States)

    Information about the SFBWQP Sears Point Tidal Marsh Restoration Project: Phase I project, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.

  2. Measuring and modeling exposure from environmental radiation on tidal flats

    International Nuclear Information System (INIS)

    Gould, T.J.; Hess, C.T.

    2005-01-01

    To examine the shielding effects of the tide cycle, a high pressure ion chamber was used to measure the exposure rate from environmental radiation on tidal flats. A theoretical model is derived to predict the behavior of exposure rate as a function of time for a detector placed one meter above ground on a tidal flat. The numerical integration involved in this derivation results in an empirical formula which implies exposure rate ∝tan-1(sint). We propose that calculating the total exposure incurred on a tidal flat requires measurements of only the slope of the tidal flat and the exposure rate when no shielding occurs. Experimental results are consistent with the model

  3. The structure of turbulence in a rapid tidal flow.

    Science.gov (United States)

    Milne, I A; Sharma, R N; Flay, R G J

    2017-08-01

    The structure of turbulence in a rapid tidal flow is characterized through new observations of fundamental statistical properties at a site in the UK which has a simple geometry and sedate surface wave action. The mean flow at the Sound of Islay exceeded 2.5 m s -1 and the turbulent boundary layer occupied the majority of the water column, with an approximately logarithmic mean velocity profile identifiable close to the seabed. The anisotropic ratios, spectral scales and higher-order statistics of the turbulence generally agree well with values reported for two-dimensional open channels in the laboratory and other tidal channels, therefore providing further support for the application of universal models. The results of the study can assist in developing numerical models of turbulence in rapid tidal flows such as those proposed for tidal energy generation.

  4. On tidal phenomena in a strong gravitational field

    International Nuclear Information System (INIS)

    Mashoon, B.

    1975-01-01

    A simple framework based on the concept of quadrupole tidal potential is presented for the calculation of tidal deformation of an extended test body in a gravitational field. This method is used to study the behavior of an initially faraway nonrotating spherical body that moves close to a Schwarzschild or an extreme Kerr black hole. In general, an extended body moving in an external gravitational field emits gravitational radiation due to its center of mass motion, internal tidal deformation, and the coupling between the internal and center of mass motions. Estimates are given of the amount of tidal radiation emitted by the body in the gravitational fields considered. The results reported in this paper are expected to be of importance in the dynamical evolution of a dense stellar system with a massive black hole in its center

  5. On tidal radius determination for a globular cluster

    International Nuclear Information System (INIS)

    Ninkovic, S.

    1985-01-01

    A tidal radius determination for a globular cluster based on its density minimum, which is caused by the galactic tidal forces and derivable from a model of the Galaxy, is proposed. Results obtained on the basis of the Schmidt model for two clusters are in a satisfactory agreement with those obtained earlier by means of other methods. A mass determination for the clusters through the tidal radius, when the latter one is identified with the cluster perigalactic distance, yields unusually large mass values. Probably, the tidal radius should be identified with the instantaneous galactocentric distance. Use of models more recent than the Schmidt one indicates that a globular cluster may contain a significant portion of an invisible interstellar matter. (author)

  6. Sears Point Tidal Marsh Restoration Project: Phase II

    Science.gov (United States)

    Information about the SFBWQP Sears Point Tidal Marsh Restoration Project: Phase II, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.

  7. Observation of Tidal Effects on LWIR Radiance Above the Mesopause

    National Research Council Canada - National Science Library

    Wintersteiner, Peter

    2007-01-01

    ..., and season The local-time dependence, in particular, suggests a role for atmospheric tides using a tidal model, Global Scale Wave Model, and our non-GTE ARC rode, we modeled the 15 Om radiance...

  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......, the accuracy of the global tidal models decreases by several centimeters in the Polar Regions. In particular, it has a large impact on the quality of the satellite altimeter sea surface heights in these regions (ERS1/2, Envisat, CryoSat-2, SARAL/AltiKa and the future Sentinel-3 mission). Better knowledge...... of the tides improves the quality of the high latitudes altimeter sea surface heights and of all derived products, such as the altimetry-derived geostrophic currents, the mean sea surface and the mean dynamic topography. In addition, accurate tidal models are highly strategic information for ever...

  9. 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...

  10. Stranded oil in coastal sediments: permeation in tidal flats

    National Research Council Canada - National Science Library

    Harper, J. R; Humphrey, B

    1986-01-01

    Physical/sedimentological parameters determining the retention and penetration oil slicks in fine sediments were examined experimentally in natural and reconstituted cores, set up in a simulated tidal system...

  11. Planet formation, orbital evolution and planet-star tidal interaction

    OpenAIRE

    Lin, D. N. C.; Papaloizou, J. C. B.; Bryden, G.; Ida, S.; Terquem, C.

    1998-01-01

    We consider several processes operating during the late stages of planet formation that can affect observed orbital elements. Disk-planet interactions, tidal interactions with the central star, long term orbital instability and the Kozai mechanism are discussed.

  12. 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.

  13. Oregon Tidal Wetland vegetation and edaphic data 2010 - 2012

    Data.gov (United States)

    U.S. Environmental Protection Agency — Data includes edaphic and vegetation field data from four Oregon tidal wetlands. National Wetlands Inventory (NWI) classification: low marsh, high marsh, and...

  14. Bedload transport in an inlet channel during a tidal cycle

    DEFF Research Database (Denmark)

    Ernstsen, V. B.; Becker, M.; Winter, C.

    2007-01-01

      Based on high-resolution swath bathymetry measurements at centimetre-scale precision conducted during a tidal cycle in a dune field in the Grådyb tidal inlet channel in the DanishWadden Sea, a simple tool to calculate bedload transport is presented. Bedload transport was related to simultaneous...... variations in grain-size composition of the mobilised sediment should be taken into account by sediment transport formulae....

  15. Tidal Current Energy Resource Assessment Around Buton Island, Southeast Sulawesi, Indonesia

    OpenAIRE

    Ribal, Agustinus; Amir, Amir Kamal; Toaha, Syamsuddin; Kusuma, Jeffry; Khaeruddin

    2017-01-01

    International Journal bereputasi An early stage of assessing tidal current energy resources is carried out in this present work. Tidal current power is estimated around Buton Island, Southeast Sulawesi province, Indonesia. Two-dimensional, depth-integrated of Advanced Circulation (ADCIRC) model has been used to simulate tidal elevation and barotropic tidal current around the island. Green???s function approach has been used to improve eight tidal constituents on the open boundary condition...

  16. The prediction of the hydrodynamic performance of tidal current turbines

    International Nuclear Information System (INIS)

    Xiao, B Y; Zhou, L J; Xiao, Y X; Wang, Z W

    2013-01-01

    Nowadays tidal current energy is considered to be one of the most promising alternative green energy resources and tidal current turbines are used for power generation. Prediction of the open water performance around tidal turbines is important for the reason that it can give some advice on installation and array of tidal current turbines. This paper presents numerical computations of tidal current turbines by using a numerical model which is constructed to simulate an isolated turbine. This paper aims at studying the installation of marine current turbine of which the hydro-environmental impacts influence by means of numerical simulation. Such impacts include free-stream velocity magnitude, seabed and inflow direction of velocity. The results of the open water performance prediction show that the power output and efficiency of marine current turbine varies from different marine environments. The velocity distribution should be clearly and the suitable unit installation depth and direction be clearly chosen, which can ensure the most effective strategy for energy capture before installing the marine current turbine. The findings of this paper are expected to be beneficial in developing tidal current turbines and array in the future

  17. The environmental interactions of tidal and wave energy generation devices

    International Nuclear Information System (INIS)

    Frid, Chris; Andonegi, Eider; Depestele, Jochen; Judd, Adrian; Rihan, Dominic; Rogers, Stuart I.; Kenchington, Ellen

    2012-01-01

    Global energy demand continues to grow and tidal and wave energy generation devices can provide a significant source of renewable energy. Technological developments in offshore engineering and the rising cost of traditional energy means that offshore energy resources will be economic in the next few years. While there is now a growing body of data on the ecological impacts of offshore wind farms, the scientific basis on which to make informed decisions about the environmental effects of other offshore energy developments is lacking. Tidal barrages have the potential to cause significant ecological impacts particularly on bird feeding areas when they are constructed at coastal estuaries or bays. Offshore tidal stream energy and wave energy collectors offer the scope for developments at varying scales. They also have the potential to alter habitats. A diversity of designs exist, including floating, mid-water column and seabed mounted devices, with a variety of moving-part configurations resulting in a unique complex of potential environmental effects for each device type, which are discussed to the extent possible. - Highlights: ► We review the environmental impacts of tidal barrages and fences, tidal stream farms and wave energy capture devices. ► Impacts on habitats, species and the water column, and effects of noise and electromagnetic fields are considered. ► Tidal barrages can cause significant impacts on bird feeding areas when constructed at coastal estuaries or bays. ► Wave energy collectors can alter water column and sea bed habitats locally and over large distances.

  18. Tidal energy, a renewable energy within hand reach

    International Nuclear Information System (INIS)

    Danielo, O.

    2011-01-01

    Tide energy and oceanic current energy represent a strong potentiality for a few countries in the world including France. In the domain of tidal energy there are 2 strategies. The first one is based on the search for the lowest power production cost in order to contribute efficiently to the country's energy mix. Generally this strategy leads to the construction of tidal dams. The second strategy is based on the search for the lowest environmental impact. This strategy is economically competitive only in places where electrical power is expensive like isolated islands. This strategy is illustrated by the tidal power station of the Alderney island. In fact the amount of energy delivered by a tidal power station depends on the rise of the tide and on the surface of the dam. It appears that tidal dams require less surface that hydroelectric power plants. The energy of oceanic currents like Gulf Stream or the thermal energy of oceans or wave power are very little exploited now but represent a potentiality higher by several orders of magnitude than tidal energy. (A.C.)

  19. Resonant Tidal Forcing in Close Binaries: Implications for CVs

    Science.gov (United States)

    Ford, K. E. Saavik; McKernan, Barry; Schwab, Elliana

    2018-01-01

    Resonant tidal forcing occurs when the tidal forcing frequency of a binary matches a quadrupolar oscillation mode of one of the binary members and energy is transferred from the orbit of the binary to the mode. Tidal locking permits ongoing resonant driving of modes even as binary orbital parameters change. At small binary separations during tidal lock, a significant fraction of binary orbital energy can be deposited quickly into a resonant mode and the binary decays faster than via the emission of gravitational radiation alone. Here we discuss some of the implications of resonant tidal forcing for the class of binaries known as Cataclysmic Variable (CV) stars. We show that resonant tidal forcing of the donor’s Roche lobe could explain the observed 2‑3hr period gap in CVs, assuming modest orbital eccentricities are allowed (eb ∼ 0.03), and can be complementary or an alternative to, existing models. Sudden collapse of the companion orbit, yielding a Type Ia supernova is disfavoured, since Hydrogen is not observed in Type Ia supernova spectra. Therefore, resonance must generally be truncated, probably via mass loss from the Roche lobe or orbital perturbation, ultimately producing a short period CV containing an ’overheated’ white dwarf.

  20. Tidal interaction of black holes and Newtonian viscous bodies

    International Nuclear Information System (INIS)

    Poisson, Eric

    2009-01-01

    The tidal interaction of a (rotating or nonrotating) black hole with nearby bodies produces changes in its mass, angular momentum, and surface area. Similarly, tidal forces acting on a Newtonian, viscous body do work on the body, change its angular momentum, and part of the transferred gravitational energy is dissipated into heat. The equations that describe the rate of change of the black-hole mass, angular momentum, and surface area as a result of the tidal interaction are compared with the equations that describe how the tidal forces do work, torque, and produce heat in the Newtonian body. The equations are strikingly similar, and unexpectedly, the correspondence between the Newtonian-body and black-hole results is revealed to hold in near-quantitative detail. The correspondence involves the combination k 2 τ of 'Love quantities' that incorporate the details of the body's internal structure; k 2 is the tidal Love number, and τ is the viscosity-produced delay between the action of the tidal forces and the body's reaction. The combination k 2 τ is of order GM/c 3 for a black hole of mass M; it does not vanish, in spite of the fact that k 2 is known to vanish individually for a nonrotating black hole.

  1. 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.

  2. Assessment of Kinetic Tidal Energy Resources Using SELFE

    Directory of Open Access Journals (Sweden)

    Manasa Ranjan Behera

    2014-09-01

    Full Text Available An investigation is carried out to study the theoretical tidal stream energy resource in the Singapore Strait to support the search for renewable energy in the effort to reduce the carbon footprints in the Southeast Asia. The tidal hydrodynamics in the Singapore Strait has been simulated using a Semi-implicit Eulerian-Lagrangian Finite-Element (SELFE model solving the 3D shallow water equations with Boussinesq approximations. Potential sites, with high tidal current (2.5 m/s and suitable for Tidal Energy Converter (TEC array installation to generate sustainable energy, have been identified. Further, various operational factors for installation of Tidal Energy Converters are considered before computing the theoretical power output for a typical TEC array. An approximate estimation of the possible theoretical power extraction from a TEC array shows an energy potential of up to 4.36% of the total energy demand of Singapore in 2011. Thus, the study suggests a detailed investigation of potential sites to quantify the total tidal stream energy potential in the Singapore Strait.

  3. 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).

  4. Tidal Love Numbers of Neutron Stars

    International Nuclear Information System (INIS)

    Hinderer, Tanja

    2008-01-01

    For a variety of fully relativistic polytropic neutron star models we calculate the star's tidal Love number k 2 . 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 stars.

  5. Stingray tidal stream energy device - phase 3

    International Nuclear Information System (INIS)

    2005-01-01

    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)

  6. 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.

  7. On the ecogeomorphological feedbacks that control tidal channel network evolution in a sandy mangrove setting

    Science.gov (United States)

    van Maanen, B.; Coco, G.; Bryan, K. R.

    2015-01-01

    An ecomorphodynamic model was developed to study how Avicennia marina mangroves influence channel network evolution in sandy tidal embayments. The model accounts for the effects of mangrove trees on tidal flow patterns and sediment dynamics. Mangrove growth is in turn controlled by hydrodynamic conditions. The presence of mangroves was found to enhance the initiation and branching of tidal channels, partly because the extra flow resistance in mangrove forests favours flow concentration, and thus sediment erosion in between vegetated areas. The enhanced branching of channels is also the result of a vegetation-induced increase in erosion threshold. On the other hand, this reduction in bed erodibility, together with the soil expansion driven by organic matter production, reduces the landward expansion of channels. The ongoing accretion in mangrove forests ultimately drives a reduction in tidal prism and an overall retreat of the channel network. During sea-level rise, mangroves can potentially enhance the ability of the soil surface to maintain an elevation within the upper portion of the intertidal zone, while hindering both the branching and headward erosion of the landward expanding channels. The modelling results presented here indicate the critical control exerted by ecogeomorphological interactions in driving landscape evolution. PMID:26339195

  8. 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.

  9. Estuary-wide genetic stock distribution and 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...

  10. 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

  11. Site condition, structure, and growth of baldcypress along tidal/non-tidal salinity gradients

    Science.gov (United States)

    Krauss, K.W.; Duberstein, J.A.; Doyle, T.W.; Conner, W.H.; Day, Richard H.; Inabinette, L.W.; Whitbeck, J.L.

    2009-01-01

    This report documents changes in forest structure and growth potential of dominant trees in salt-impacted tidal and non-tidal baldcypress wetlands of the southeastern United States. We inventoried basal area and tree height, and monitored incremental growth (in basal area) of codominant baldcypress (Taxodium distichum) trees monthly, for over four years, to examine the inter-relationships among growth, site fertility, and soil physico-chemical characteristics. We found that salinity, soil total nitrogen (TN), flood duration, and flood frequency affected forest structure and growth the greatest. While mean annual site salinity ranged from 0.1 to 3.4 ppt, sites with salinity concentrations of 1.3 ppt or greater supported a basal area of less than 40 m2/ha. Where salinity was < 0.7 ppt, basal area was as high as 87 m2/ha. Stand height was also negatively affected by higher salinity. However, salinity related only to soil TN concentrations or to the relative balance between soil TN and total phosphorus (TP), which reached a maximum concentration between 1.2 and 2.0 ppt salinity. As estuarine influence shifts inland with sea-level rise, forest growth may become more strongly linked to salinity, not only due to salt effects but also as a consequence of site nitrogen imbalance.

  12. Trophic relationships in tidal flat areas: To what extent are tidal flats dependent on imported food?

    Science.gov (United States)

    Asmus, Harald; Asmus, Ragnhild M.

    In four intertidal areas of 'Königshafen' (island of Sylt, FRG), biomass and production of macrozoobenthos were measured monthly in 1980 and 1984. The areas were characterized by different macrofauna assemblages ( Nereis-Corophium belt, seagrass bed, Arenicola flat and mussel bed). Biomass and production of macrofauna were partitioned with regard to food preference of single species as well as to the food availability within their habitat. In the Nereis-Corophium belt, seagrass bed and the Arenicola flat, most of the secondary production of the macrofauna was formed by grazing animals. Secondary production of mussel beds was nearly 10 times higher than in the other three assemblages. The suspension feeder assemblage depended on planktonic food imported from outside the bay. Considering the secondary production of the total tidal flat area, suspension feeders dominated the other trophic groups, indicating a key position of this group relative to the other macrofaunal assemblages. Mussel beds regulate the seston input to other communities situated further landward. Because of this dominance of the suspension feeder group, the energy and material flow of the total tidal flat is strongly dependent on the seston input from the coastal waters of the North Sea or from other parts of the Wadden Sea.

  13. Dynamical Studies of N-Body Gravity and Tidal Dissipation in the TRAPPIST-1 Star System

    Science.gov (United States)

    Nayak, Michael; Kuettel, Donald H.; Stebler, Shane T.; Udrea, Bogdan

    2018-01-01

    To date, we have discovered a total of 2,729 planetary systems that contain more than 3,639 known exoplanets [1]. A majority of these are defined as compact systems, containing multiple exoplanets within 0.25 AU of the central star. It has been shown that tightly packed exoplanets avoid colliding due to long-term resonance-induced orbit stability [2]. However, due to extreme proximity, these planets experience intense gravitational forces from each other that are unprecedented within our own solar system, which makes the existence of exomoons doubtful. We present the results of an initial study evaluating dynamical stability of potential exomoons within such highly compact systems.This work is baselined around TRAPPIST-1, an ultra-cool dwarf star that hosts seven temperate terrestrial planets, three of which are in the habitable zone, orbiting within 0.06 AU [3]. N-body simulations place a grid of test particles varying semi-major axis, eccentricity, and inclination around the three habitable zone planets. We find that most exomoons with semi-major axes less than half the Hill sphere of their respective planet are stable over 10 kyrs, with several stable over 300 kyrs.However, in compact systems, tidal influences from other planets can compete with tidal effects from the primary planet, resulting in possible instabilities and massive amounts of tidal dissipation. We investigate these effects with a large grid search that incorporates exomoon radius, tidal quality factor and a range of planet rigidities. Results of simulations that combine n-body gravity effects with both planetary and satellite tides are presented and contrasted with n-body results. Finally, we examine long-term stability (> 1Myrs) of the stable subset of test particles from the n-body simulation with the addition of tidal dissipation, to determine if exomoons can survive around planets e, f, and g in the TRAPPIST-1 system.[1] Schneider (2017). The Extrasolar Planets Encyclopedia. http

  14. Observed tidal currents on the continental shelf off the east coast of India

    Science.gov (United States)

    Jithin, A. K.; Unnikrishnan, A. S.; Fernando, V.; Subeesh, M. P.; Fernandes, R.; Khalap, S.; Narayan, S.; Agarvadekar, Y.; Gaonkar, M.; Tari, P.; Kankonkar, A.; Vernekar, S.

    2017-06-01

    In the present study, we analysed 9-month long data from Acoustic Doppler Current Profilers (ADCP) deployed on the shelf off the east coast of India to study the characteristics of tidal currents in the region. The ADCPs were deployed at about 100-150 m depths off Cuddalore (CD, 12.0°N), Ramayapatnam (RM, 15.0°N), Kakinada (KN, 16.3°N) and South of Gopalpur (SG, 18.6°N). Tidal currents in the region are mainly semidiurnal in nature and dominant constituent is M2. Semimajor axes of barotropic tidal ellipses of M2 is about 1.9 cms-1 in the southernmost ADCP location (off CD) and it is about 4.0 cms-1 in the northernmost ADCP location (off SG), which indicate a northward increase of tidal currents. Baroclinic spectra show high energy at tidal frequencies, which suggests the presence of internal tides on the shelf, particularly in the semidiurnal band. Semidiurnal internal tides of about 8-15 cms-1 are observed at different locations and the magnitude is relatively large on the shelf off SG in the northern part of the shelf, which is primarily due to large barotropic forcing on the north. The semidiurnal internal tides are found to be intensified at the bottom, particularly on the shelf off SG and RM. The computed ratio of slope of internal wave characteristics (c) and topographic slope (γ) indicates that large near-critical regions present surrounding the ADCP locations off SG and RM could be the possible reason of bottom intensification at these two locations. EOF analysis shows that observed semidiurnal internal tides are dominated by the first baroclinic mode, where it accounts for about 70-80% of semidiurnal internal tide variability on the shelf off SG and CD, whereas the contribution of the first mode is relatively small (43-50%) on the shelf off KN and RM. Enhanced small-scale vertical shear is observed at the ADCP locations associated with multimode structure of semidiurnal internal tides. Semidiurnal internal tides show a spring-neap variability on the

  15. Numerical Simulation of an Oscillatory-Type Tidal Current Powered Generator Based on Robotic Fish Technology

    Directory of Open Access Journals (Sweden)

    Ikuo Yamamoto

    2017-10-01

    Full Text Available The generation of clean renewable energy is becoming increasingly critical, as pollution and global warming threaten the environment in which we live. While there are many different kinds of natural energy that can be harnessed, marine tidal energy offers reliability and predictability. However, harnessing energy from tidal flows is inherently difficult, due to the harsh environment. Current mechanisms used to harness tidal flows center around propeller-based solutions but are particularly prone to failure due to marine fouling from such as encrustations and seaweed entanglement and the corrosion that naturally occurs in sea water. In order to efficiently harness tidal flow energy in a cost-efficient manner, development of a mechanism that is inherently resistant to these harsh conditions is required. One such mechanism is a simple oscillatory-type mechanism based on robotic fish tail fin technology. This uses the physical phenomenon of vortex-induced oscillation, in which water currents flowing around an object induce transverse motion. We consider two specific types of oscillators, firstly a wing-type oscillator, in which the optimal elastic modulus is being sort. Secondly, the optimal selection of shape from 6 basic shapes for a reciprocating oscillating head-type oscillator. A numerical analysis tool for fluid structure-coupled problems—ANSYS—was used to select the optimum softness of material for the first type of oscillator and the best shape for the second type of oscillator, based on the exhibition of high lift coefficients. For a wing-type oscillator, an optimum elastic modulus for an air-foil was found. For a self-induced vibration-type mechanism, based on analysis of vorticity and velocity distribution, a square-shaped head exhibited a lift coefficient of more than two times that of a cylindrically shaped head. Analysis of the flow field clearly showed that the discontinuous flow caused by a square-headed oscillator results in

  16. 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

  17. Tidal dissipation in the subsurface ocean of Enceladus

    Science.gov (United States)

    Matsuyama, I.; Hay, H.; Nimmo, F.; Kamata, S.

    2017-12-01

    Icy satellites of the outer solar system have emerged as potential habitable worlds due to the presence of subsurface oceans. As a long-term energy source, tidal heating in these oceans can influence the survivability of subsurface oceans, and the thermal, rotational, and orbital evolution of these satellites. Additionally, the spatial and temporal variation of tidal heating has implications for the interior structure and spacecraft observations. Previous models for dissipation in thin oceans are not generally applicable to icy satellites because either they ignore the presence of an overlying solid shell or use a thin shell membrane approximation. We present a new theoretical treatment for tidal dissipation in thin oceans with overlying shells of arbitrary thickness and apply it to Enceladus. The shell's resistance to ocean tides increases with shell thickness, reducing tidal dissipation as expected. Both the magnitude of energy dissipation and the resonant ocean thicknesses decrease as the overlying shell thickness increases, as previously shown using a membrane approximation. In contrast to previous work based on the traditional definition of the tidal quality factor, Q, our new definition is consistent with higher energy dissipation for smaller Q, and introduces a lower limit on Q. The dissipated power and tides are not in phase with the forcing tidal potential due to the delayed ocean response. The phase lag depends on the Rayleigh friction coefficient and ocean and shell thicknesses, which implies that phase lag observations can be used to constrain these parameters. Eccentricity heating produces higher dissipation near the poles, while obliquity heating produces higher dissipation near the equator, in contrast to the dissipation patterns in the shell. The time-averaged surface distribution of tidal heating can generate lateral shell thickness variations, providing an additional constraint on the Rayleigh friction coefficient. Explaining the endogenic power

  18. On effects produced by tidal power plants upon environmental conditions in adjacent sea areas

    International Nuclear Information System (INIS)

    Nekrasov, A.V.; Romanenkov, D.A.

    1997-01-01

    Consideration is given to the change in natural (oceanographic) environmental conditions due to the transformation of the tidal oscillations structure resulting from erection and operation of tidal power plants (TPP). The relevant transformation of tidal movements encompasses practically all its main characteristics: amplitudes, phases and spectral composition of sea level oscillations, as well as the similar parameters of tidal currents and also the intensity and positioning of extremes zones. The changes in positioning and width of the inter-tidal zone, the inter-tidal zone regime, mutual arrangement of mixed, stratified and transient frontal zones, transportation of suspended matter and bottom sedimentation, owing to residual tidal currents, sea ice characteristics, air these changes can be estimated on the basis of mathematical predictive modelling of tidal characteristics transformed by a contemplated tidal power plant. Some results are presented for the Russian large-scale TPP projects in the White and Okhotsk seas. (author)

  19. A Simple, Inexpensive, and Field-Relevant Microcosm Tidal Simulator for Use in Marsh Macrophyte Studies

    Directory of Open Access Journals (Sweden)

    Rachel M. MacTavish

    2014-10-01

    Full Text Available Premise of the study: A microcosm unit with tidal simulation was developed to address the challenge of maintaining ecologically relevant tidal regimes while performing controlled greenhouse experiments on smooth cordgrass, Spartina alterniflora. Methods and Results: We designed a simple, inexpensive, easily replicated microcosm unit with tidal simulation and tested whether S. alterniflora growth in microcosms with tidal simulation was similar to that of tidally influenced plants in the field on Sapelo Island, Georgia. After three months of exposure to either natural or simulated tidal treatment, plants in microcosms receiving tidal simulation had similar stem density, height, and above- and belowground biomass to plants in field plots. Conclusions: The tidal simulator developed may provide an inexpensive, effective method for conducting studies on S. alterniflora and other tidally influenced plants in controlled settings to be used not only to complement field studies, but also in locations without coastal access.

  20. A simple, inexpensive, and field-relevant microcosm tidal simulator for use in marsh macrophyte studies.

    Science.gov (United States)

    MacTavish, Rachel M; Cohen, Risa A

    2014-11-01

    A microcosm unit with tidal simulation was developed to address the challenge of maintaining ecologically relevant tidal regimes while performing controlled greenhouse experiments on smooth cordgrass, Spartina alterniflora. • We designed a simple, inexpensive, easily replicated microcosm unit with tidal simulation and tested whether S. alterniflora growth in microcosms with tidal simulation was similar to that of tidally influenced plants in the field on Sapelo Island, Georgia. After three months of exposure to either natural or simulated tidal treatment, plants in microcosms receiving tidal simulation had similar stem density, height, and above- and belowground biomass to plants in field plots. • The tidal simulator developed may provide an inexpensive, effective method for conducting studies on S. alterniflora and other tidally influenced plants in controlled settings to be used not only to complement field studies, but also in locations without coastal access.

  1. Modified Saint-Venant equations for flow simulation in tidal rivers

    Directory of Open Access Journals (Sweden)

    Xiao-qin Zhang

    2012-03-01

    Full Text Available Flow in tidal rivers periodically propagates upstream or downstream under tidal influence. Hydrodynamic models based on the Saint-Venant equations (the SVN model are extensively used to model tidal rivers. A force-corrected term expressed as the combination of flow velocity and the change rate of the tidal level was developed to represent tidal effects in the SVN model. A momentum equation incorporating with the corrected term was derived based on Newton's second law. By combing the modified momentum equation with the continuity equation, an improved SVN model for tidal rivers (the ISVN model was constructed. The simulation of a tidal reach of the Qiantang River shows that the ISVN model performs better than the SVN model. It indicates that the corrected force derived for tidal effects is reasonable; the ISVN model provides an appropriate enhancement of the SVN model for flow simulation of tidal rivers.

  2. 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.

  3. Microarray Analyses of Genes Differentially Expressed by Diet (Black Beans and Soy Flour during Azoxymethane-Induced Colon Carcinogenesis in Rats

    Directory of Open Access Journals (Sweden)

    Elizabeth A. Rondini

    2012-01-01

    Full Text Available We previously demonstrated that black bean (BB and soy flour (SF-based diets inhibit azoxymethane (AOM-induced colon cancer. The objective of this study was to identify genes altered by carcinogen treatment in normal-appearing colonic mucosa and those attenuated by bean feeding. Ninety-five male F344 rats were fed control (AIN diets upon arrival. At 4 and 5 weeks, rats were injected with AOM (15 mg/kg or saline and one week later administered an AIN, BB-, or SF-based diet. Rats were sacrificed after 31 weeks, and microarrays were conducted on RNA isolated from the distal colonic mucosa. AOM treatment induced a number of genes involved in immunity, including several MHC II-associated antigens and innate defense genes (RatNP-3, Lyz2, Pla2g2a. BB- and SF-fed rats exhibited a higher expression of genes involved in energy metabolism and water and sodium absorption and lower expression of innate (RatNP-3, Pla2g2a, Tlr4, Dmbt1 and cell cycle-associated (Cdc2, Ccnb1, Top2a genes. Genes involved in the extracellular matrix (Col1a1, Fn1 and innate immunity (RatNP-3, Pla2g2a were induced by AOM in all diets, but to a lower extent in bean-fed animals. This profile suggests beans inhibit colon carcinogenesis by modulating cellular kinetics and reducing inflammation, potentially by preserving mucosal barrier function.

  4. Intracellular photoreceptive site for blue light-induced cell division in protonemata of the fern Adiantum [Pteridophyta]: Further analyses by polarized light irradiation and cell centrifugation

    International Nuclear Information System (INIS)

    Kadota, A.; Fushimi, Y.; Wada, M.

    1986-01-01

    The intracellular localization of the photoreceptive site for blue light-induced cell division in single-celled protonemata of Adiantum capillus-veneris L. was investigated using polarized light irradiation and protonemal cell centrifugation. The response to irradiation with polarized blue light showed no dependence on the direction of light polarization. However, centrifugation of the protonemata followed by microbeam irradiation showed that the site of blue light perception could be displaced together with the nucleus. Centrifugal treatment changed the distribution of intracellular organelles at the time of light exposure and basipetally displaced the nucleus about 90μm. This treatment had no effect on the induction of cell division with blue light if the protonemata were centrifuged again acropetally after the light treatment. Microbeam (30×30 μm2) irradiation with blue light of the apical 45–75 βm region, the receptive site of blue light in non-centrifuged cell, did not induce cell division. However, cell division was induced by irradiation of the nucleus-containing region, indicating that the photoreceptive site was displaced together with the nucleus by the centrifugation. These results suggest that the blue light receptor regulating cell division in Adiantum protonemata is not likely to be located on the plasma membrane. (author)

  5. Paracoccus aestuarii sp. nov., isolated from tidal flat sediment.

    Science.gov (United States)

    Roh, Seong Woon; Nam, Young-Do; Chang, Ho-Won; Kim, Kyoung-Ho; Kim, Min-Soo; Shin, Kee-Sun; Yoon, Jung-Hoon; Oh, Hee-Mock; Bae, Jin-Woo

    2009-04-01

    A Gram-negative micro-organism, designated strain B7(T), was isolated from tidal flat sediment and subjected to a polyphasic taxonomic study involving morphological, physiological, biochemical and 16S rRNA gene sequence analyses. A phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain B7(T) belonged to the genus Paracoccus and was closely related phylogenetically to Paracoccus marcusii MH1(T) (97.5 % sequence similarity), Paracoccus marinus KKL-A5(T) (97.5 %), Paracoccus haeundaensis BC74171(T) (97.3 %), Paracoccus carotinifaciens E-396(T) (97.3 %), Paracoccus homiensis DD-R11(T) (97.2 %), Paracoccus seriniphilus MBT-A4(T) (96.9 %) and other type strains of the genus Paracoccus (95.2-96.7 %). The G+C content of the genomic DNA and the major isoprenoid quinone of the type strain were 62.0 mol% and ubiquinone-10, respectively. The major fatty acid components were C(18 : 1)omega7c (68.9 %) and C(18 : 0) (18.1 %); this profile, with C(18 : 1)omega7c as the predominant fatty acid, was characteristic of members of the genus Paracoccus. The 16S rRNA gene sequence analysis, DNA-DNA hybridization studies and physiological and biochemical tests identified genotypic and phenotypic differences between strain B7(T) and recognized Paracoccus species. On the basis of these data, therefore, strain B7(T) represents a novel species of the genus Paracoccus, for which the name Paracoccus aestuarii sp. nov. is proposed. The type strain is B7(T) (=KCTC 22049(T)=DSM 19484(T)=JCM 15119(T)).

  6. Tidal and Ionospheric Contributions in GUVI O/N2 wave-4 Signals and Implications for F-region Plasma Density Variability

    Science.gov (United States)

    Oberheide, J.; Krier, C. S.; Gan, Q.; Nischal, N.; Zhang, Y.; Chang, L. C.

    2017-12-01

    The longitude/local time modulation of the column number density ratio of atomic oxygen to molecular nitrogen (O/N2 ratio) observed by GUVI/TIMED shows several features that are inconsistent with the known tidal structures in the thermosphere. The zonal wavenumber 4 (wave-4) pattern that is usually associated with the eastward propagating DE3 and SE2 nonmigrating tides is propagating westward and the diagnosed relative O/N2 amplitudes of 5-10% are larger than expected from a thermosphere-tidal coupling perspective. Two recent studies from the GUVI team already established the leading source of the bogus wave-4 tidal signals: ionospheric contamination of the O/N2 ratio derived from GUVI's optical observations caused by radiative O+ recombination in the F-region. However, the apparent westward propagation in the wave-4 GUVI O/N2 ratio remained unexplained since the ionospheric contamination pattern itself is controlled by the DE3 and SE2 tides in the F-region plasma and should thus propagate eastward. This paper revisits the problem by separating the "true" thermospheric tidal signal in the GUVI O/N2 ratio from the ionospheric contamination using the TIMED-based empirical climatological tidal model of the thermosphere (CTMT) and supporting COSMIC TEC tidal diagnostics. As such, it provides new observational information about the impact of tidally-induced composition changes on ionospheric variability. Furthermore, it is shown that the superposition of DE3, SE2, and SPW4 from ionospheric and thermospheric sources produces the apparent westward propagation in O/N2, which will be helpful to interpret the forthcoming GOLD and ICON observations.

  7. Long-term organic carbon sequestration in tidal marsh sediments is dominated by old-aged allochthonous inputs in a macrotidal estuary.

    Science.gov (United States)

    Van de Broek, Marijn; Vandendriessche, Caroline; Poppelmonde, Dries; Merckx, Roel; Temmerman, Stijn; Govers, Gerard

    2018-02-12

    Tidal marshes are vegetated coastal ecosystems that are often considered as hotspots of atmospheric CO 2 sequestration. Although large amounts of organic carbon (OC) are indeed being deposited on tidal marshes, there is no direct link between high OC deposition rates and high OC sequestration rates due to two main reasons. First, the deposited OC may become rapidly decomposed once it is buried and, second, a significant part of preserved OC may be allochthonous OC that has been sequestered elsewhere. In this study we aimed to identify the mechanisms controlling long-term OC sequestration in tidal marsh sediments along an estuarine salinity gradient (Scheldt estuary, Belgium and the Netherlands). Analyses of deposited sediments have shown that OC deposited during tidal inundations is up to millennia old. This allochthonous OC is the main component of OC that is effectively preserved in these sediments, as indicated by the low radiocarbon content of buried OC. Furthermore, OC fractionation showed that autochthonous OC is decomposed on a decadal timescale in saltmarsh sediments, while in freshwater marsh sediments locally produced biomass is more efficiently preserved after burial. Our results show that long-term OC sequestration is decoupled from local biomass production in the studied tidal marsh sediments. This implies that OC sequestration rates are greatly overestimated when they are calculated based on short-term OC deposition rates, which are controlled by labile autochthonous OC inputs. Moreover, as allochthonous OC is not sequestered in-situ, it does not contribute to active atmospheric CO 2 sequestration in these ecosystems. A correct assessment of the contribution of allochthonous OC to the total sedimentary OC stock in tidal marsh sediments as well as a correct understanding of the long-term fate of locally produced OC are both necessary to avoid overestimations of the rate of in-situ atmospheric CO 2 sequestration in tidal marsh sediments. © 2018 John

  8. Infrared emission and tidal interactions of spiral galaxies

    International Nuclear Information System (INIS)

    Byrd, G.G.

    1987-01-01

    Computer simulations of tidal interactions of spiral galaxies are used to attempt to understand recent discoveries about infrared (IR) emitting galaxies. It is found that the stronger tidal perturbation by a companion the more disk gas clouds are thrown into nucleus crossing orbits and the greater the velocity jumps crossing spiral arms. Both these tidally created characteristics would create more IR emission by high speed cloud collisions and more IR via effects of recently formed stars. This expectation at greater tidal perturbation matches the observation of greater IR emission for spiral galaxies with closer and/or more massive companions. The greater collision velocities found at stronger perturbations on the models will also result in higher dust temperature in the colliding clouds. In the IR pairs examined, most have only one member, the larger, detected and when both are detected, the larger is always the more luminous. In simulations and in a simple analytic description of the strong distance dependence of the tidal force, it is found that the big galaxy of a pair is more strongly affected than the small

  9. Tidal tilts observations in the Gran Sasso underground laboratory

    International Nuclear Information System (INIS)

    Iafolla, V.; Nozzoli, S.; Milyukov, V.

    2001-01-01

    A new tilt meter, based on the technology for building a space-borne high-sensitivity accelerometer and manufactured at IFSI/CNR, has a been operating during several years in the INFN Gran Sasso underground laboratory. The results of the analysis of a three-year data set, processed with the program package ETERNA, to estimate earth tidal parameters are reported. For the best series of data (1998) tide measurement accuracies are: 0.5-1% for the M 2 (lunar principal) amplitude and 3-4% for the O 1 (lunar declination) amplitude. The tilt meter installed at a depth of 1400 m shows no clear evidence of meteorological effects. Observed tidal parameters are compared with theoretical tidal parameters predicted for a non-hydrostatic inelastic Earth model and demonstrate good agreement for the M 2 component. Due to the high accuracy of the tidal components prediction (better than 1%) tidal measurements were used to estimate the long-term stability of the instrument response

  10. Geometro-thermodynamics of tidal charged black holes

    International Nuclear Information System (INIS)

    Gergely, Laszlo Arpad; Pidokrajt, Narit; Winitzki, Sergei

    2011-01-01

    Tidal charged spherically symmetric vacuum brane black holes are characterized by their mass m and tidal charge q, an imprint of the five-dimensional Weyl curvature. For q>0 they are formally identical to the Reissner-Nordstroem black hole of general relativity. We study the thermodynamics and thermodynamic geometries of tidal charged black holes and discuss similarities and differences as compared to the Reissner-Nordstroe m black hole. As a similarity, we show that (for q>0) the heat capacity of the tidal charged black hole diverges on a set of measure zero of the parameter space, nevertheless both the regularity of the Ruppeiner metric and a Poincare stability analysis show no phase transition at those points. The thermodynamic state spaces being different indicates that the underlying statistical models could be different. We find that the q<0 parameter range, which enhances the localization of gravity on the brane, is thermodynamically preferred. Finally we constrain for the first time the possible range of the tidal charge from the thermodynamic limit on gravitational radiation efficiency at black hole mergers. (orig.)

  11. 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.

  12. 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.

  13. A numerical study of equilibrium states in tidal network morphodynamics

    Science.gov (United States)

    Xu, Fan; Coco, Giovanni; Zhou, Zeng; Tao, Jianfeng; Zhang, Changkuan

    2017-12-01

    The long-term morphodynamic evolution of tidal networks on tidal flats is investigated using a two-dimensional numerical model. We explore the physical processes related to the development of the morphology and the presence of equilibrium configurations. Tidal networks are simulated over a rectangular domain representing a tidal platform, a different setting compared to estuaries (subject to riverine influence) and lagoons (offshore bars constricting the flow). In the early and middle phases of the tidal network evolution, large sediment patches with rhombus-like shape form and gradually migrate in the flood direction, even though the overall sediment flux is ebb-directed. A cross-section-averaged "equilibrium" state is asymptotically approached after about 500 years. The area and peak discharge of the lower flat cross-sections at year 500 approximately show a 1:1 relationship, which is in agreement with field observations. We also show that model results are consistent with the Q-A relationship (peak discharge Q versus cross-sectional area A), which is obtained under the assumption of a constant Chézy friction.

  14. Heartbeat stars, tidally excited oscillations and resonance locking

    Science.gov (United States)

    Fuller, Jim

    2017-12-01

    Heartbeat stars are eccentric binary stars in short-period orbits whose light curves are shaped by tidal distortion, reflection and Doppler beaming. Some heartbeat stars exhibit tidally excited oscillations and present new opportunities for understanding the physics of tidal dissipation within stars. We present detailed methods to compute the forced amplitudes, frequencies and phases of tidally excited oscillations in eccentric binary systems. Our methods (i) factor out the equilibrium tide for easier comparison with observations, (ii) account for rotation using the traditional approximation, (iii) incorporate non-adiabatic effects to reliably compute surface luminosity perturbations, (iv) allow for spin-orbit misalignment and (v) correctly sum over contributions from many oscillation modes. We also discuss why tidally excited oscillations (TEOs) are more visible in hot stars with surface temperatures T ≳ 6500 K, and we derive some basic probability theory that can be used to compare models with data in a statistical manner. Application of this theory to heartbeat systems can be used to determine whether observed TEOs can be explained by chance resonances with stellar oscillation modes, or whether a resonance locking process is operating.

  15. Searching for Tidal Tails in Galactic Dwarf Spheroidal Galaxies

    Science.gov (United States)

    Martínez-Delgado, David; Aparicio, A.; Gomez-Flechoso, Maria A.

    The formation of the Galactic halo is currently best explained by the combination of two scenarios which previously were regarded as competing models. Based on the kinematics of metal-poor halo field stars, Eggen, Lynden-Bell & Sandage (ELS, 1962) proposed that the halo formed during a rapid, smooth collapse from a homogeneous primordial medium. Searle & Zinn (SZ, 1978) argued a halo formation via the gradual merging of many sub-galactic fragments. The SZ scenario has been strengthened by the observational evidence accumulated during the past decade. The discovery of the Sagittarius dwarf galaxy (Ibata, Gilmore & Irwin 1994), in a process of dissolving into the Galactic halo, argued in favour that accretion events can take place in the Milky Way. The possibility that accretion events may leave observable fossil records in the halo is also supported by theoretical models of tidally disrupted dSph satellites (Johnston, Spergel & Hernquist 1995; Oh, Lin & Aarseth 1995; Piatek & Pryor 1995). We present our preliminary results of a long-term project to investigate the process of accretion and tidal disruption of dSph satellites in the Galactic halo and, in particular, to search for new tidal tails in a sample of nearby dSph satellites of the Milky Way. The presence of a possible tidal debris in Ursa Minor and Sculptor dSphs and the results of our survey for a tidal extension along the NW semimajor axis of Saggitarius is discussed.

  16. Tidal effects in the evolution of natural satellites

    Science.gov (United States)

    Mignard, F.

    1981-03-01

    The effects of tidal friction in the orbital evolution of natural satellites are considered, and constraints set by tidal effects on the evolution of the earth-moon system, Phobos and Deimos and the Pluto-Charon system are discussed. The energy dissipated by tidal friction is shown to lead eventually to a stable state in a planetary system determined by the initial angular velocities and orbital directions of the planet and satellite(s), with the satellite in a circular equatorial orbit with the same face turned to the planet in the final state of orbital evolution. For the case of the Martian system, results of integrations of satellite motion into the past and future are presented which demonstrate the decrease in the eccentricity and orbital inclination with respect to the Martian equator of Phobos, which may have been captured from an orbit in the plane of the ecliptic or formed by accretion in the Mars equatorial plane, and its eventual fate in a collision with Mars. The effects of tidal dissipation on the history of the inclination of the lunar orbit on the ecliptic, the obliquity of the ecliptic and the eccentricity of the lunar orbit are also illustrated, and the secular acceleration of the moon and the lengthening of the day are noted. Finally, the observed day length on Pluto close to the revolution period of Charon is discussed as an example of the final state of tidal evolution.

  17. 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.

  18. Metabolic regulatory oscillations in intertidal green seaweed Ulva lactuca against tidal cycles.

    Science.gov (United States)

    Gupta, Vishal; Kushwaha, Hemant R

    2017-11-27

    The survival of wetland plant species largely relies on physiological adaptations essential for submergence and desiccation. Intertidal seaweeds, unlike terrestrial plants, have unique adaptations to submergence and can also sustain desiccation arising from tidal rhythms. This study determined the differential metabolic regulations in the inter-tidal seaweed species Ulva lactuca against the submergence and desiccation. During desiccation, the relative water content of the algal thalli declined with concomitant increase in reactive oxygen species (ROS) and lipid peroxidation. Nevertheless, the trends reversed during recovery on re-submergence and attained homeostasis. Metabolite profiling of U. lactuca revealed desiccation induced balance in energy reserve utilization by adjusting carbohydrate metabolism and switch over to ammonia metabolism. Upon re-submergence, thalli showed an increase in fermentative metabolites, pyruvate-alanine conversion, and the GABA shunt. Prolonged submergence induced substrate level phosphorylation mediated sugar biosynthesis while continuing the alternative carbon flux through fermentative metabolism, an increase in osmoprotectants glycine and betaine, sulfur bearing compounds cysteine and hypotaurine, and phenolic compound coniferaldehyde. The determined metabolic regulations in U. lactuca for submergence tolerance provide insights into potential evolutionarily conserved protective mechanisms across the green lineage and also highlights the possible role of sulfur oxoforms as strong free radical scavengers.

  19. CLIMATE INSTABILITY ON TIDALLY LOCKED EXOPLANETS

    International Nuclear Information System (INIS)

    Kite, Edwin S.; Manga, Michael; Gaidos, Eric

    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 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 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 gases. Both

  20. 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

  1. Climate destabilization on tidally locked exoplanets

    Science.gov (United States)

    Kite, E. S.; Gaidos, E.; Manga, M.

    2011-12-01

    We show that strong day-night surface temperature contrasts on planets with surfaces allow positive feedbacks that can potentially destabilize planetary climate. Geologically rapid 10^3 - fold atmospheric pressure shifts may be possible. Habitable-zone planets maintain stable surface liquid water over geological time through equilibrium between greenhouse-gas consumption by weathering, and resupply by other processes. All reported small-radius exoplanets, and anticipated M-dwarf habitable-zone rocky planets, should be tidally locked. We will discuss two different feedbacks that can destabilize climate equilibrium on planets in 1:1 spin-orbit resonance. (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 runway positive feedback between pressure, surface temperature, and weathering rate near the substellar point takes place - 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, further decreases in pressure can occur. This substellar dissolution feedback (SDF) can also cause a runaway climate shift. We use an idealized energy balance model to illustrate the scope of these instabilities. In this simplified model, the weathering runaway can shrink 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, and can only cause runaway changes for small, deep oceans and highly soluble atmospheric gases. Both instabilities are suppressed if the atmosphere has a high radiative efficiency. Our results are most relevant for atmospheres that are thin, have low greenhouse-gas radiative efficiency

  2. Tidal variations of O2 Atmospheric and OH(6-2 airglow and temperature at mid-latitudes from SATI observations

    Directory of Open Access Journals (Sweden)

    M. J. López-González

    2005-12-01

    Full Text Available Airglow observations with a Spectral Airglow Temperature Imager (SATI, installed at the Sierra Nevada Observatory (37.06° N, 3.38° W at 2900-m height, have been used to investigate the presence of tidal variations at mid-latitudes in the mesosphere/lower thermosphere region. Diurnal variations of the column emission rate and vertically averaged temperature of the O2 Atmospheric (0-1 band and of the OH Meinel (6-2 band from 5 years (1998-2003 of observations have been analysed. From these observations a clear tidal variation of both emission rates and rotational temperatures is inferred. It is found that the amplitude of the daily variation for both emission rates and temperatures is greater from late autumn to spring than during summer. The amplitude decreases by more than a factor of two during summer and early autumn with respect to the amplitude in the winter-spring months. Although the tidal modulations are preferentially semidiurnal in both rotational temperatures and emission rates during the whole year, during early spring the tidal modulations seem to be more consistent with a diurnal modulation in both rotational temperatures and emission rates. Moreover, the OH emission rate from late autumn to early winter has a pattern suggesting both diurnal and semidiurnal tidal modulations.

  3. 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).

  4. Tidal change in the energy of a spherical galaxy

    International Nuclear Information System (INIS)

    Namboodiri, P.M.S.; Kochlar, R.K.

    1990-01-01

    Tidal effects of a massive perturber on a satellite galaxy have been studied by numerical simulations. The model consists of a spherical satellite galaxy and a point-mass perturber and the encounter is non-penetrating. A wide range of density ratios and eccentricities of the orbit have been used. The disruption of the satellite galaxy has been observed when the numerical value of the fractional change in the energy is greater than two. The energy change shows smooth variation with time in the case of unbound orbits and irregular variation in the bound orbit cases. It is shown that, for a constant pericentric distance, increasing the density ratio decreases the tidal effects, and for a given density ratio an increase in the eccentricity decreases the tidal effects. N-body results are compared with predictions of analytical estimates. (author)

  5. Stellar dynamics and tidal disruption events in galactic nuclei

    Directory of Open Access Journals (Sweden)

    Alexander T.

    2012-12-01

    Full Text Available 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 new dynamical results that are changing our understanding of dynamics near a massive black hole, and may well be relevant for tidal disruption dynamics.

  6. N-Body simulations of tidal encounters between stellar systems

    International Nuclear Information System (INIS)

    Rao, P.D.; Ramamani, N.; Alladin, S.M.

    1985-10-01

    N-Body simulations have been performed to study the tidal effects of a primary stellar system on a secondary stellar system of density close to the Roche density. Two hyperbolic, one parabolic and one elliptic encounters have been simulated. The changes in energy, angular momentum, mass distribution, and shape of the secondary system have been determined in each case. The inner region containing about 40% of the mass was found to be practically unchanged and the mass exterior to the tidal radius was found to escape. The intermediate region showed tidal distension. The thickness of this region decreased as we went from hyperbolic encounters to the elliptic encounter keeping the distance of closest approach constant. The numerical results for the fractional change in energy have been compared with the predictions of the available analytic formulae and the usefulness and limitations of the formulae have been discussed. (author)

  7. 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.

  8. Radiocarbon dating of plant macrofossils from tidal-marsh sediment

    Science.gov (United States)

    Kemp, A.C.; Nelson, Alan R.; Horton, B.P.

    2013-01-01

    Tidal-marsh sediment is an archive of Holocene environmental changes, including movements of sea and land levels, and extreme events such as hurricanes, earthquakes, and tsunamis. Accurate and precise radiocarbon dating of environmental changes is necessary to estimate rates of change and the recurrence interval (frequency) of events. Plant macrofossils preserved in growth position (or deposited soon after death) in tidal-marsh sediment are ideal samples for dating such changes. In this chapter, we focus on the selection of plant macrofossils for radiocarbon dating and the application of ages from different types of macrofossils to varied research projects, and make recommendations for selection and preparation of tidal-marsh samples for dating.

  9. On the Papaloizou-Pringle instability in tidal disruption events

    Science.gov (United States)

    Nealon, Rebecca; Price, Daniel J.; Bonnerot, Clément; Lodato, Giuseppe

    2018-02-01

    We demonstrate that the compact, thick disc formed in a tidal disruption event may be unstable to non-axisymmetric perturbations in the form of the Papaloizou-Pringle instability. We show this can lead to rapid redistribution of angular momentum that can be parametrized in terms of an effective Shakura-Sunyaev α parameter. For remnants that have initially weak magnetic fields, this may be responsible for driving mass accretion prior to the onset of the magnetorotational instability. For tidal disruptions around a 106 M⊙ black hole, the measured accretion rate is super-Eddington but is not sustainable over many orbits. We thus identify a method by which the torus formed in tidal disruption event may be significantly accreted before the magnetorotational instability is established.

  10. ON THE EFFICIENCY OF THE TIDAL STIRRING MECHANISM FOR THE ORIGIN OF DWARF SPHEROIDALS: DEPENDENCE ON THE ORBITAL AND STRUCTURAL PARAMETERS OF THE PROGENITOR DISKY DWARFS

    International Nuclear Information System (INIS)

    Kazantzidis, Stelios; Lokas, Ewa L.; Callegari, Simone; Mayer, Lucio; Moustakas, Leonidas A.

    2011-01-01

    The tidal stirring model posits the formation of dwarf spheroidal galaxies (dSphs) via the tidal interactions between late-type, rotationally supported dwarfs and Milky-Way-sized host galaxies. Using a comprehensive set of collisionless N-body simulations, we investigate the efficiency of the tidal stirring mechanism for the origin of dSphs. In particular, we examine the degree to which the tidal field of the primary galaxy affects the sizes, masses, shapes, and kinematics of the disky dwarfs for a range of dwarf orbital and structural parameters. Our study is the first to employ self-consistent, equilibrium models for the progenitor dwarf galaxies constructed from a composite distribution function and consisting of exponential stellar disks embedded in massive, cosmologically motivated dark matter halos. Exploring a wide variety of dwarf orbital configurations and initial structures, we demonstrate that in the majority of cases the disky dwarfs experience significant mass loss and their stellar distributions undergo a dramatic morphological, as well as dynamical, transformation. Specifically, the stellar components evolve from disks to bars and finally to pressure-supported, spheroidal systems with kinematic and structural properties akin to those of the classic dSphs in the Local Group (LG) and similar environments. The self-consistency of the adopted dwarf models is crucial for confirming this complex transformation process via tidally induced dynamical instabilities and impulsive tidal heating of the stellar distribution. Our results suggest that such tidal transformations should be common occurrences within the currently favored cosmological paradigm and highlight the key factor responsible for an effective metamorphosis to be the strength of the tidal shocks at the pericenters of the orbit. We also demonstrate that the combination of short orbital times and small pericentric distances, characteristic of dwarfs being accreted by their hosts at high redshift

  11. Nonrotating black hole in a post-Newtonian tidal environment

    International Nuclear Information System (INIS)

    Taylor, Stephanne; Poisson, Eric

    2008-01-01

    We examine the motion and tidal dynamics of a nonrotating black hole placed within a post-Newtonian external spacetime. The black hole's gravity is described accurately to all orders in Gm/c 2 r, where m is the black-hole mass and r is the distance to the black hole. The tidal perturbation created by the external environment is treated as a small perturbation. At a large distance from the black hole, the gravitational field of the external distribution of matter is assumed to be sufficiently weak to be adequately described by the (first) post-Newtonian approximation to general relativity. There, the black hole is treated as a monopole contribution to the total gravitational field. There exists an overlap in the domains of validity of each description, and the black-hole and post-Newtonian metrics are matched in the overlap. The matching procedure produces (i) a justification of the statement that a nonrotating black hole is a post-Newtonian monopole; (ii) a complete characterization of the coordinate transformation between the inertial, barycentric frame and the accelerated, black-hole frame; (iii) the equations of motion for the black hole; and (iv) the gravito-electric and gravito-magnetic tidal fields acting on the black hole. We first calculate the equations of motion and tidal fields by making no assumptions regarding the nature of the post-Newtonian environment; this could contain a continuous distribution of matter (so as to model a galactic core) or any number of condensed bodies. We next specialize our discussion to a situation in which the black hole is a member of a post-Newtonian two-body system. As an application of our results, we examine the geometry of the deformed event horizon and calculate the tidal heating of the black hole, the rate at which it acquires mass as a result of its tidal interaction with the companion body.

  12. ENHANCED TIDAL DISRUPTION RATES FROM MASSIVE BLACK HOLE BINARIES

    International Nuclear Information System (INIS)

    Chen Xian; Liu, F. K.; Madau, Piero; Sesana, Alberto

    2009-01-01

    'Hard' massive black hole (MBH) binaries embedded in steep stellar cusps can shrink via three-body slingshot interactions. We show that this process will inevitably be accompanied by a burst of stellar tidal disruptions, at a rate that can be several orders of magnitude larger than that appropriate for a single MBH. Our numerical scattering experiments reveal that (1) a significant fraction of stars initially bound to the primary hole are scattered into its tidal disruption loss cone by gravitational interactions with the secondary hole, an enhancement effect that is more pronounced for very unequal mass binaries; (2) about 25% (40%) of all strongly interacting stars are tidally disrupted by an MBH binary of mass ratio q = 1/81 (q = 1/243) and eccentricity 0.1; and (3) two mechanisms dominate the fueling of the tidal disruption loss cone, a Kozai nonresonant interaction that causes the secular evolution of the stellar angular momentum in the field of the binary, and the effect of close encounters with the secondary hole that change the stellar orbital parameters in a chaotic way. For a hard MBH binary of 10 7 M sun and mass ratio 10 -2 , embedded in an isothermal stellar cusp of velocity dispersion σ * = 100 km s -1 , the tidal disruption rate can be as large as N-dot * ∼1 yr -1 . This is 4 orders of magnitude higher than estimated for a single MBH fed by two-body relaxation. When applied to the case of a putative intermediate-mass black hole inspiraling onto Sgr A*, our results predict tidal disruption rates N-dot * ∼0.05-0.1 yr -1 .

  13. Breakdown of Hydrostatic Assumption in Tidal Channel with Scour Holes

    Directory of Open Access Journals (Sweden)

    Chunyan Li

    2016-10-01

    Full Text Available Hydrostatic condition is a common assumption in tidal and subtidal motions in oceans and estuaries.. Theories with this assumption have been largely successful. However, there is no definite criteria separating the hydrostatic from the non-hydrostatic regimes in real applications because real problems often times have multiple scales. With increased refinement of high resolution numerical models encompassing smaller and smaller spatial scales, the need for non-hydrostatic models is increasing. To evaluate the vertical motion over bathymetric changes in tidal channels and assess the validity of the hydrostatic approximation, we conducted observations using a vessel-based acoustic Doppler current profiler (ADCP. Observations were made along a straight channel 18 times over two scour holes of 25 m deep, separated by 330 m, in and out of an otherwise flat 8 m deep tidal pass leading to the Lake Pontchartrain over a time period of 8 hours covering part of the diurnal tidal cycle. Out of the 18 passages over the scour holes, 11 of them showed strong upwelling and downwelling which resulted in the breakdown of hydrostatic condition. The maximum observed vertical velocity was ~ 0.35 m/s, a high value in a tidal channel, and the estimated vertical acceleration reached a high value of 1.76×10-2 m/s2. Analysis demonstrated that the barotropic non-hydrostatic acceleration was dominant. The cause of the non-hydrostatic flow was the that over steep slopes. This demonstrates that in such a system, the bathymetric variation can lead to the breakdown of hydrostatic conditions. Models with hydrostatic restrictions will not be able to correctly capture the dynamics in such a system with significant bathymetric variations particularly during strong tidal currents.

  14. 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. © 2015 The Authors. Journal of Biophotonics published by WILEY-VCH Verlag.

  15. Integration of cell line and clinical trial genome-wide analyses supports a polygenic architecture of Paclitaxel-induced sensory peripheral neuropathy.

    Science.gov (United States)

    Wheeler, Heather E; Gamazon, Eric R; Wing, Claudia; Njiaju, Uchenna O; Njoku, Chidiamara; Baldwin, Robert Michael; Owzar, Kouros; Jiang, Chen; Watson, Dorothy; Shterev, Ivo; Kubo, Michiaki; Zembutsu, Hitoshi; Winer, Eric P; Hudis, Clifford A; Shulman, Lawrence N; Nakamura, Yusuke; Ratain, Mark J; Kroetz, Deanna L; Cox, Nancy J; Dolan, Mary Eileen

    2013-01-15

    We sought to show the relevance of a lymphoblastoid cell line (LCL) model in the discovery of clinically relevant genetic variants affecting chemotherapeutic response by comparing LCL genome-wide association study (GWAS) results to clinical GWAS results. A GWAS of paclitaxel-induced cytotoxicity was conducted in 247 LCLs from the HapMap Project and compared with a GWAS of sensory peripheral neuropathy in patients with breast cancer (n = 855) treated with paclitaxel in the Cancer and Leukemia Group B (CALGB) 40101 trial. Significant enrichment was assessed by permutation resampling analysis. We observed an enrichment of LCL cytotoxicity-associated single-nucleotide polymorphisms (SNP) in the sensory peripheral neuropathy-associated SNPs from the clinical trial with concordant allelic directions of effect (empirical P = 0.007). Of the 24 SNPs that overlap between the clinical trial (P architecture of related traits in patients. ©2012 AACR.

  16. Distinct roles of the pepper hypersensitive induced reaction protein gene CaHIR1 in disease and osmotic stress, as determined by comparative transcriptome and proteome analyses.

    Science.gov (United States)

    Jung, Ho Won; Lim, Chae Woo; Lee, Sung Chul; Choi, Hyong Woo; Hwang, Cheol Ho; Hwang, Byung Kook

    2008-01-01

    A Capsicum annuum hypersensitive induced reaction protein1 (CaHIR1) was recently proposed as a positive regulator of hypersensitive cell death in plants. Overexpression of CaHIR1 in transgenic Arabidopsis plants conferred enhanced resistance against the hemi-biotrophic Pseudomonas syringae pv. tomato (Pst) and the biotrophic Hyaloperonospora parasitica. Infection by avirulent Pseudomonas strains carrying avrRpm1 or avrRpt2 caused enhanced resistance responses in transgenic plants, suggesting that CaHIR1 is involved in basal disease resistance in a race-nonspecific manner. H. parasitica exhibited low levels of asexual sporulation on CaHIR1 seedlings. In contrast, transgenic plants were susceptible not only to the necrotrophic fungal pathogen Botrytis cinerea but were also sensitive to osmotic stress caused by high salinity and drought. To identify proteins whose expression was altered by CaHIR1 overexpression in Arabidopsis leaves, a quantitative comparative proteome analysis using two-dimensional gel electrophoresis coupled with mass spectrometry was performed. Of about 400 soluble proteins, 11 proteins involved in several metabolic pathways were up- or down-regulated by CaHIR1 overexpression. Genes encoding glycine decarboxylase (At2g35370) and an unidentified protein (At2g03440), which were strongly upregulated in CaHIR1-overexpressing Arabidopsis, were also differentially induced at the transcriptional level by Pst infection. Arabidopsis carbonic anhydrase (At3g01500), highly similar to tobacco salicylic acid-binding protein 3, was up-regulated by CaHIR1 overexpression. The activity of an anti-oxidant enzyme, cooper/zinc superoxide dismutase (At2g28190), was also attenuated in transgenic Arabidopsis by CaHIR1 overexpression. Together, these results suggest that CaHIR1 overexpression in Arabidopsis mediates plant responses to biotrophic, hemi-biotrophic and necrotrophic pathogens, as well as to osmotic stress in different ways.

  17. Bedform evolution in a tidal inlet referred from wavelet analysis

    DEFF Research Database (Denmark)

    Fraccascia, Serena; Winter, Christian; Ernstsen, Verner Brandbyge

    2011-01-01

    Bedforms are common morphological features in subaqueous and aeolian environments and their characterization is commonly the first step to better understand forcing factors acting in the system. The aim of this study was to investigate the spectral characteristics of compound bedforms in a tidal...... 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...

  18. Spatiotemporal Information Organization and Visualization on Tidal Level

    Science.gov (United States)

    Huang, B.; Zhang, Y.; Wang, Y.; Liu, Q.

    2015-07-01

    The amount and location of oceanographic stations vary in different time and the observation information of the same station shows temporality. Hence, ocean observation information has strong spatiotemporal characteristics. This article firstly introduces storage strategy and representation method of spatiotemporal information on tidal level. Then the prototype system was built with the ability of storing, updating, analyzing, and early warning of tidal level in Shandong Peninsula of China. The system achieves the inquiry and visualization of realtime and historical information of oceanographic stations, which provides technical support for oceanographers and decisionmakers.

  19. Extreme Value Analysis of Tidal Stream Velocity Perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Harding, Samuel; Thomson, Jim; Polagye, Brian; Richmond, Marshall C.; Durgesh, Vibhav; Bryden, Ian

    2011-04-26

    This paper presents a statistical extreme value analysis of maximum velocity perturbations from the mean flow speed in a tidal stream. This study was performed using tidal velocity data measured using both an Acoustic Doppler Velocimeter (ADV) and an Acoustic Doppler Current Profiler (ADCP) at the same location which allows for direct comparison of predictions. The extreme value analysis implements of a Peak-Over-Threshold method to explore the effect of perturbation length and time scale on the magnitude of a 50-year perturbation.

  20. End-tidal carbon dioxide monitoring in pediatrics - clinical applications.

    Directory of Open Access Journals (Sweden)

    Bhende M

    2001-07-01

    Full Text Available End-tidal CO2 monitoring is an exciting non-invasive technology that is more commonly used in the emergency department, intensive care unit and in the prehospital setting. Its main use has been in verifying endotracheal tube position, during mechanical ventilation and cardiopulmonary resuscitation, but it is being studied and used for other purposes as well. The new American Heart Association guidelines require secondary confirmation of proper tube placement in all patients by exhaled CO2 immediately after intubation and during transport. This article covers the clinical applications of end-tidal CO2 monitoring with special reference to the paediatric patient.

  1. Environmental impact assessment of Kachchh tidal power project

    International Nuclear Information System (INIS)

    Yadav, Ramanand; Lal, B.B.

    1995-01-01

    The Kachchh tidal power development project is a single-basin, single -effect and ebb generation development by construction of a tidal power barrage of about 3.25 km length across Hansthal creek. The project may disturb the ecosystem of the region. The paper deals in detail the environmental impacts of the project on climate, water velocity, flow and sedimentation pattern, water quality, flora and fauna, fishery, tourism and recreation, wild life, public health and socio-economic conditions. (author). 4 refs., 1 fig., 2 tabs

  2. Probing Quiescent Massive Black Holes: Insights from Tidal Disruption Events

    OpenAIRE

    Gezari, Suvi; Strubbe, Linda; Bloom, Joshua S.; Grindlay, J. E.; Soderberg, Alicia; Elvis, Martin; Coppi, Paolo; Lawrence, Andrew; Ivezic, Zeljko; Merritt, David; Komossa, Stefanie; Halpern, Jules; Eracleous, Michael

    2009-01-01

    Tidal disruption events provide a unique probe of quiescent black holes in the nuclei of distant galaxies. The next generation of synoptic surveys will yield a large sample of flares from the tidal disruption of stars by massive black holes that will give insights to four key science questions: 1) What is the assembly history of massive black holes in the universe? 2) Is there a population of intermediate mass black holes that are the primordial seeds of supermassive black holes? 3) How can w...

  3. Modern sedimentary environments in a large tidal estuary, Delaware Bay

    Science.gov (United States)

    Knebel, H.J.

    1989-01-01

    Data from an extensive grid of sidescan-sonar records reveal the distribution of sedimentary environments in the large, tidally dominated Delaware Bay estuary. Bathymetric features of the estuary include large tidal channels under the relatively deep (> 10 m water depth) central part of the bay, linear sand shoals (2-8 m relief) that parallel the sides of the tidal channels, and broad, low-relief plains that form the shallow bay margins. The two sedimentary environments that were identified are characterized by either (1) bedload transport and/or erosion or (2) sediment reworking and/or deposition. Sand waves and sand ribbons, composed of medium to coarse sands, define sites of active bedload transport within the tidal channels and in gaps between the linear shoals. The sand waves have spacings that vary from 1 to 70 m, amplitudes of 2 m or less, and crestlines that are usually straight. The orientations of the sand waves and ribbons indicate that bottom sediment movement may be toward either the northwest or southeast along the trends of the tidal channels, although sand-wave asymmetry indicates that the net bottom transport is directed northwestward toward the head of the bay. Gravelly, coarse-grained sediments, which appear as strongly reflective patterns on the sonographs, are also present along the axes and flanks of the tidal channels. These coarse sediments are lag deposits that have developed primarily where older strata were eroded at the bay floor. Conversely, fine sands that compose the linear shoals and muddy sands that cover the shallow bay margins appear mainly on the sonographs either as smooth featureless beds that have uniform light to moderate shading or as mosaics of light and dark patches produced by variations in grain size. These acoustic and textural characteristics are the result of sediment deposition and reworking. Data from this study (1) support the hypothesis that bed configurations under deep tidal flows are functions of current

  4. Can We Probe the Conductivity of the Lithosphere and Upper Mantle Using Satellite Tidal Magnetic Signals?

    Science.gov (United States)

    Schnepf, N. R.; Kuvshinov, A.; Sabaka, T.

    2015-01-01

    A few studies convincingly demonstrated that the magnetic fields induced by the lunar semidiurnal (M2) ocean flow can be identified in satellite observations. This result encourages using M2 satellite magnetic data to constrain subsurface electrical conductivity in oceanic regions. Traditional satellite-based induction studies using signals of magnetospheric origin are mostly sensitive to conducting structures because of the inductive coupling between primary and induced sources. In contrast, galvanic coupling from the oceanic tidal signal allows for studying less conductive, shallower structures. We perform global 3-D electromagnetic numerical simulations to investigate the sensitivity of M2 signals to conductivity distributions at different depths. The results of our sensitivity analysis suggest it will be promising to use M2 oceanic signals detected at satellite altitude for probing lithospheric and upper mantle conductivity. Our simulations also suggest that M2 seafloor electric and magnetic field data may provide complementary details to better constrain lithospheric conductivity.

  5. Worldwide tidal current energy developments and opportunities for Canada's Pacific coast. Paper no. IGEC-1-039

    International Nuclear Information System (INIS)

    Pearce, N.

    2005-01-01

    Recent rapid advances of tidal current energy extraction (TCEE) technologies and resource analyses suggest in excess of 20,000 GWh/annum of electricity may be realistically exploitable in the near term off Canada's West Coast. Moreover, because tidal currents have a semidiurnal (or, in some locations, diurnal) periodicity, and can be predicted and quantified on a spatial and temporal basis, this resource confers a distinct advantage over most other renewables, and, therefore, may achieve supply security. In this study, TCEE technologies are assessed on the basis of energy delivered, environmental intrusion and economic viability. As such, relevant issues including resource characteristics, site selection, conversion efficiencies, capacity factors, power densities, hydrodynamic feedbacks, and grid integration are addressed. (author)

  6. 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.

  7. 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.

  8. Relative dispersion of clustered drifters in a small micro-tidal estuary

    Science.gov (United States)

    Suara, Kabir; Chanson, Hubert; Borgas, Michael; Brown, Richard J.

    2017-07-01

    Small tide-dominated estuaries are affected by large scale flow structures which combine with the underlying bed generated smaller scale turbulence to significantly increase the magnitude of horizontal diffusivity. Field estimates of horizontal diffusivity and its associated scales are however rare due to limitations in instrumentation. Data from multiple deployments of low and high resolution clusters of GPS-drifters are used to examine the dynamics of a surface flow in a small micro-tidal estuary through relative dispersion analyses. During the field study, cluster diffusivity, which combines both large- and small-scale processes ranged between, 0.01 and 3.01 m2/s for spreading clusters and, -0.06 and -4.2 m2/s for contracting clusters. Pair-particle dispersion, Dp2, was scale dependent and grew as Dp2 ∼ t1.83 in streamwise and Dp2 ∼ t0.8 in cross-stream directions. At small separation scale, pair-particle (d law and became weaker as separation scale increases. Pair-particle diffusivity was described as Kp ∼ d1.01 and Kp ∼ d0.85 in the streamwise and cross-stream directions, respectively for separation scales ranging from 0.1 to 10 m. Two methods were used to identify the mechanism responsible for dispersion within the channel. The results clearly revealed the importance of strain fields (stretching and shearing) in the spreading of particles within a small micro-tidal channel. The work provided input for modelling dispersion of passive particle in shallow micro-tidal estuaries where these were not previously experimentally studied.

  9. On feathers, bifurcations and shells: the dynamics of tidal streams across the mass scale

    Science.gov (United States)

    Amorisco, N. C.

    2015-06-01

    I present an organic description of the spectrum of regimes of collisionless tidal streams and define the orderings between the relevant physical quantities that shape their morphology. Three fundamental dichotomies are identified and described in the form of dimensionless inequalities. These govern (i) the speed of the stream's growth, (ii) the internal coherence of the stream and (iii) its thickness or opening angle, within and outside the orbital plane. The mechanisms through which such main qualitative properties are regulated and the relevant limiting cases are analysed. For example, the slope of the host's density profile strongly influences the speed of the stream's growth, in both length and width, as steeper density profiles enhance differential streaming. Internal coherence is the natural requirement for the appearance of substructure and overdensities in tidal debris, and I concentrate on the characteristic `feathering' typical of streams of star clusters. Overdensities and substructures are associated with minima in the relative streaming velocity of the stream members. For streams with high circularity, these are caused by the epicyclic oscillations of stars; however, for highly non-circular progenitor's orbits, internal substructure is caused by the oscillating differences in energy and actions with which material is shed at different orbital phases of the progenitor. This modulation results in different streaming speeds along the tidal arm: the streakline of material shed between two successive apocentric passages is folded along its length, pulled at its centre by the faster differential streaming of particles released near pericentre, which are therefore more widely scattered. When the stream is coherent enough, the same mechanism is potentially capable of generating a bimodal profile in the density distributions of the longer wraps of more massive progenitors, which I dub `bifurcations'. The conditions that allow streams to be internally coherent

  10. 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...... on the centimeter level, station corrections regarding the Earth tides and the ocean tidal loading have to be applied. Models for global corrections esp. for the body tides are available and sufficient, but local corrections regarding the effect of the adjacent shelf area still have to be inferred from additional...... 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...

  11. Adélie penguin foraging location predicted by tidal regime switching.

    Science.gov (United States)

    Oliver, Matthew J; Irwin, Andrew; Moline, Mark A; Fraser, William; Patterson, Donna; Schofield, Oscar; Kohut, Josh

    2013-01-01

    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.

  12. Tidal impact on the division of river discharge and distributary channels in the Mahakam Delta

    NARCIS (Netherlands)

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

    2011-01-01

    Bifurcations in tidally influenced deltas distribute river discharge over downstream channels, asserting a strong control over terrestrial runoff to the coastal ocean. Whereas the mechanics of river bifurcations is well-understood, junctions in tidal channels have received comparatively little

  13. Tidal extension and sea-level rise: recommendations for a research agenda

    Science.gov (United States)

    Ensign, Scott H.; Noe, Gregory

    2018-01-01

    Sea-level rise is pushing freshwater tides upstream into formerly non-tidal rivers. This tidal extension may increase the area of tidal freshwater ecosystems and offset loss of ecosystem functions due to salinization downstream. Without considering how gains in ecosystem functions could offset losses, landscape-scale assessments of ecosystem functions may be biased toward worst-case scenarios of loss. To stimulate research on this concept, we address three fundamental questions about tidal extension: Where will tidal extension be most evident, and can we measure it? What ecosystem functions are influenced by tidal extension, and how can we measure them? How do watershed processes, climate change, and tidal extension interact to affect ecosystem functions? Our preliminary answers lead to recommendations that will advance tidal extension research, enable better predictions of the impacts of sea-level rise, and help balance the landscape-scale benefits of ecosystem function with costs of response.

  14. Tidal circulation and salinity distribution in the Mandovi and Zuari estuaries: Case study

    Digital Repository Service at National Institute of Oceanography (India)

    Manoj, N.T.; Unnikrishnan, A.S.

    . The simulated tidally averaged salinities over the M2 tidal period for varying river discharges show that even a small freshwater influx can affect the longitudinal distribution of salinity to a great extent in this type of estuaries...

  15. Tidal influence on the diel vertical migration pattern of zooplankton in a tropical monsoonal Estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Vineetha, G.; Jyothibabu, R.; Madhu, N.V.; Kusum, K.K.; Sooria, P.M.; Shivaprasad, A.; Reny, P.D.; Deepak, M.P.

    habitats is often determined by their dominant behavioral patterns: diel vertical migration (DVM) and tidal vertical migration (TVM). The modes of these endogenous rhythms often vary among estuaries based on the river runoff and tidal characteristics...

  16. 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.

  17. Determining Tidal Phase Differences from X-Band Radar Images

    Science.gov (United States)

    Newman, Kieran; Bell, Paul; Brown, Jennifer; Plater, Andrew

    2017-04-01

    Introduction Previous work by Bell et. al. (2016) has developed a method using X-band marine radar to measure intertidal bathymetry, using the waterline as a level over a spring-neap tidal cycle. This has been used in the Dee Estuary to give a good representation of the bathymetry in the area. However, there are some sources of inaccuracy in the method, as a uniform spatial tidal signal is assumed over the entire domain. Motivation The method used by Bell et. al. (2016) applies a spatially uniform tidal signal to the entire domain. This fails to account for fine-scale variations in water level and tidal phase. While methods are being developed to account for small-scale water level variations using high resolution modelling, a method to determine tidal phase variations directly from the radar intensity images could be advantageous operationally. Methods The tidal phase has been computed using two different methods, with hourly averaged images from 2008. In the first method, the cross-correlation between each raw pixel time series and a tidal signal at a number of lags is calculated, and the lag with the highest correlation to the pixel series is recorded. For the second method, the same method of correlation is used on signals generated by tracking movement of buoys, which show up strongly in the radar image as they move on their moorings with the tidal currents. There is a broad agreement between the two methods, but validation is needed to determine the relative accuracy. The phase has also been calculated using a Fourier decomposition, and agrees broadly with the above methods. Work also needs to be done to separate areas where the recorded phase is due to tidal current (mostly subtidal areas) or due to elevation (mostly the wetting/drying signal in intertidal areas), by classifying radar intensities by the phases and amplitudes of the tides. Filtering out signal variations due to wind strength and attenuation of the radar signal will also be applied. Validation

  18. Comparative gene and protein expression analyses of a panel of cytokines in acute and chronic drug-induced liver injury in rats

    International Nuclear Information System (INIS)

    Hanafusa, Hiroyuki; Morikawa, Yuji; Uehara, Takeki; Kaneto, Masako; Ono, Atsushi; Yamada, Hiroshi; Ohno, Yasuo; Urushidani, Tetsuro

    2014-01-01

    Drug-induced liver injury (DILI) is a significant safety issue associated with medication use, and is the major cause of failures in drug development and withdrawal in post marketing. Cytokines are signaling molecules produced and secreted by immune cells and play crucial roles in the progression of DILI. Although there are numerous reports of cytokine changes in several DILI models, a comprehensive analysis of cytokine expression changes in rat liver injury induced by various compounds has, to the best of our knowledge, not been performed. In the past several years, we have built a public, free, large-scale toxicogenomics database, called Open TG-GATEs, containing microarray data and toxicity data of the liver of rats treated with various hepatotoxic compounds. In this study, we measured the protein expression levels of a panel of 24 cytokines in frozen liver of rats treated with a total of 20 compounds, obtained in the original study that formed the basis of the Open TG-GATEs database and analyzed protein expression profiles combined with mRNA expression profiles to investigate the correlation between mRNA and protein expression levels. As a result, we demonstrated significant correlations between mRNA and protein expression changes for interleukin (IL)-1β, IL-1α, monocyte chemo-attractant protein (MCP)-1/CC-chemokine ligand (Ccl)2, vascular endothelial growth factor A (VEGF-A), and regulated upon activation normal T cell expressed and secreted (RANTES)/Ccl5 in several different types of DILI. We also demonstrated that IL-1β protein and MCP-1/Ccl2 mRNA were commonly up-regulated in the liver of rats treated with different classes of hepatotoxicants and exhibited the highest accuracy in the detection of hepatotoxicity. The results also demonstrate that hepatic mRNA changes do not always correlate with protein changes of cytokines in the liver. This is the first study to provide a comprehensive analysis of mRNA–protein correlations of factors involved in

  19. Tidal and sub-tidal sea level variability at the northern shelf of the Brazilian Northeast Region.

    Science.gov (United States)

    Frota, Felipe F; Truccolo, Eliane C; Schettini, Carlos A F

    2016-09-01

    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.

  20. A modeling study of tidal energy extraction and the associated impact on tidal circulation in a multi-inlet bay system of Puget Sound

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Taiping; Yang, Zhaoqing

    2017-12-01

    Previous tidal energy projects in Puget Sound have focused on major deep channels such as Admiralty Inlet that have a larger power potential but pose greater technical challenges than minor tidal channels connecting to small sub-basins. This paper focuses on the possibility of extracting energy from minor tidal channels by using a hydrodynamic model to quantify the power potential and the associated impact on tidal circulation. The study site is a multi-inlet bay system connected by two narrow inlets, Agate Pass and Rich Passage, to the Main Basin of Puget Sound. A three-dimensional hydrodynamic model was applied to the study site and calibrated for tidal elevations and currents. We examined three energy extraction scenarios in which turbines were deployed in each of the two passages and concurrently in both. Extracted power rates and associated changes in tidal elevation, current, tidal flux, and residence time were examined. Maximum instantaneous power rates reached 250 kW, 1550 kW, and 1800 kW, respectively, for the three energy extraction scenarios. The model suggests that with the proposed level of energy extraction, the impact on tidal circulation is very small. It is worth investigating the feasibility of harnessing tidal energy from minor tidal channels of Puget Sound.

  1. A phase separation method for analyses of fluoroquinones in meats based on ultrasound-assisted salt-induced liquid-liquid microextraction and a new integrated device.

    Science.gov (United States)

    Wang, Huili; Gao, Ming; Xu, Youqu; Wang, Wenwei; Zheng, Lian; Dahlgren, Randy A; Wang, Xuedong

    2015-08-01

    Herein, we developed a novel integrated device to perform phase separation based on ultrasound-assisted, salt-induced, liquid-liquid microextraction for determination of five fluoroquinones in meats by HPLC analysis. The novel integrated device consisted of three simple HDPE (high density polyethylene) parts that were used to separate the solvent from the aqueous solution prior to retrieving the extractant. The extraction parameters were optimized using the response surface method based on central composite design: 589μL of acetone solvent, pH2.1, 4.1min extraction time and 3.5g of Na2SO4. The limits of detection were 0.056-0.64 μgkg(-1) and recoveries were 87.2-110.6% for the five fluoroquinones in muscle tissue from fish, chicken, pork and beef. This method is easily constructed from inexpensive materials, extraction efficiency is high, and the approach is compatible with HPLC analysis. Thus, it has excellent prospects for sample pre-treatment and analysis of fluoroquinones in meat samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Characterization of the genome of a phylogenetically distinct tospovirus and its interactions with the local lesion-induced host Chenopodium quinoa by whole-transcriptome analyses.

    Science.gov (United States)

    Chou, Wan-Chen; Lin, Shih-Shun; Yeh, Shyi-Dong; Li, Siang-Ling; Peng, Ying-Che; Fan, Ya-Hsu; Chen, Tsung-Chi

    2017-01-01

    Chenopodium quinoa is a natural local lesion host of numerous plant viruses, including tospoviruses (family Bunyaviridae). Groundnut chlorotic fan-spot tospovirus (GCFSV) has been shown to consistently induce local lesions on the leaves of C. quinoa 4 days post-inoculation (dpi). To reveal the whole genome of GCFSV and its interactions with C. quinoa, RNA-seq was performed to determine the transcriptome profiles of C. quinoa leaves. The high-throughput reads from infected C. quinoa leaves were used to identify the whole genome sequence of GCFSV and its single nucleotide polymorphisms. Our results indicated that GCFSV is a phylogenetically distinct tospovirus. Moreover, 27,170 coding and 29,563 non-coding sequences of C. quinoa were identified through de novo assembly, mixing reads from mock and infected samples. Several key genes involved in the modulation of hypersensitive response (HR) were identified. The expression levels of 4,893 deduced complete genes annotated using the Arabidopsis genome indicated that several HR-related orthologues of pathogenesis-related proteins, transcription factors, mitogen-activated protein kinases, and defense proteins were significantly expressed in leaves that formed local lesions. Here, we also provide new insights into the replication progression of a tospovirus and the molecular regulation of the C. quinoa response to virus infection.

  3. 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, Anni Tindahl; Murray, Andrew S.; Andersen, Thorbjørn Joest

    2010-01-01

    Depositional processes in intertidal areas are determined both by changes in sea-level and sediment supply. It is known on a millennial timescale that sedimentation normally keeps pace with sea-level rise in a subsiding tidal basin. However, little is known about whether the sedimentation can keep...... sedimentation has followed the rate of relative sea-level rise, at least over the last ~2000 years, whereas the trends in sediment accumulation rates on the sandy tidal flat in the eastern and exposed part of the lagoon are less clear. Here, there is large variability in sediment accumulation rates...

  4. 75 FR 61479 - Kendall Head Tidal Energy Project; Notice of Preliminary Permit Application Accepted for Filing...

    Science.gov (United States)

    2010-10-05

    ... Tidal Energy Project; Notice of Preliminary Permit Application Accepted for Filing and Soliciting... Federal Power Act, proposing to study the feasibility of the Kendall Head Tidal Energy Project, located in.... The proposed project would consist of: (1) 4 OCGen\\TM\\ hydrokinetic tidal devices each consisting of...

  5. 75 FR 59256 - Eastport Tidal Power LLC; Notice of Competing Preliminary Permit Application Accepted for Filing...

    Science.gov (United States)

    2010-09-27

    ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 13830-000] Eastport Tidal... Comments and Motions To Intervene September 17, 2010. On August 9, 2010, Eastport Tidal Power LLC filed an... study the feasibility of the Half Moon Cove Tidal Power Plant Project to be located in Half Moon Cove...

  6. 78 FR 44557 - Turnagain Arm Tidal Energy Corporation; Notice of Preliminary Permit Application Accepted for...

    Science.gov (United States)

    2013-07-24

    ... Tidal Energy Corporation; Notice of Preliminary Permit Application Accepted for Filing and Soliciting Comments, Motions To Intervene, and Competing Applications On February 1, 2013, the Turnagain Arm Tidal... Federal Power Act (FPA), proposing to study the feasibility of the Turnagain Arm Tidal Electric Generation...

  7. 75 FR 78236 - Pennamaquan Tidal Power, LLC; Notice of Preliminary Permit Application Accepted for Filing and...

    Science.gov (United States)

    2010-12-15

    ... Tidal Power, LLC; Notice of Preliminary Permit Application Accepted for Filing and Soliciting Comments, Motions To Intervene, and Competing Applications December 8, 2010. On November 22, 2010, Pennamaquan Tidal... Act (FPA), proposing to study the feasibility of the Pennamaquan Tidal Power Plant Project to be...

  8. Broad timescale forcing and geomorphic mediation of tidal marsh flow and temperature dynamics

    Science.gov (United States)

    Enwright, Christopher; Culberson, Steven; Burau, Jon R.

    2013-01-01

    Tidal marsh functions are driven by interactions between tides, landscape morphology, and emergent vegetation. Less often considered are the diurnal pattern of tide extremes and seasonal variation of solar insolation in the mix of tidal marsh driver interactions. This work demonstrates how high-frequency hydroperiod and water temperature variability emerges from disparate timescale interactions between tidal marsh morphology, tidal harmonics, and meteorology in the San Francisco Estuary. We compare the tidal and residual flow and temperature response of neighboring tidal sloughs, one possessing natural tidal marsh morphology, and one that is modified for water control. We show that the natural tidal marsh is tuned to lunar phase and produces tidal and fortnight water temperature variability through interacting tide, meteorology, and geomorphic linkages. In contrast, temperature variability is dampened in the modified slough where overbank marsh plain connection is severed by levees. Despite geomorphic differences, a key finding is that both sloughs are heat sinks in summer by latent heat flux-driven residual upstream water advection and sensible and long-wave heat transfer. The precession of a 335-year tidal harmonic assures that these dynamics will shift in the future. Water temperature regulation appears to be a key function of natural tidal sloughs that depends critically on geomorphic mediation. We investigate approaches to untangling the relative influence of sun versus tide on residual water and temperature transport as a function of system morphology. The findings of this study likely have ecological consequences and suggest physical process metrics for tidal marsh restoration performance.

  9. 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....

  10. 77 FR 5817 - Ocean Renewable Power Company, Tidal Energy Project, Cobscook Bay, ME

    Science.gov (United States)

    2012-02-06

    ... Company, Tidal Energy Project, Cobscook Bay, ME AGENCY: Coast Guard, DHS. ACTION: Request for comments...) 366-9826. SUPPLEMENTARY INFORMATION: Background and Purpose ORPC's tidal energy project involves... vicinity of the proposed tidal energy project. We are attempting to determine the scope of any safety...

  11. 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

  12. 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%.

  13. Residual water transport in the Marsdiep tidal inlet inferred from observations and a numerical model

    NARCIS (Netherlands)

    Sassi, M.G.; Gerkema, T.; Duran-Matute, M.; Nauw, J.J.

    2016-01-01

    At tidal inlets, large amounts of water are exchanged with the adjacent sea during the tidal cycle.The residual flows, the net effect of ebb and flood, are generally small compared with the gross flux;they vary in magnitude and sign from one tidal period to the other; and their long-term mean

  14. Classification of tidal inlets along the Central east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Reddy, N.A.; Vikas, M.; Rao, S.; JayaKumar S.

    ) as long as the alongshore sediment bypasses the tidal inlet. Classification of coastal systems in a broader view is necessary for the management of tidal inlets. There are several methods to classify tidal inlets based on different perspectives namely geo-morphological...

  15. The cross-sectional shape of tidal sandbanks: modeling and observations

    NARCIS (Netherlands)

    Roos, Pieter C.; Hulscher, Suzanne J.M.H.; Knaapen, Michiel; van Damme, Rudolf M.J.

    2004-01-01

    To improve our understanding of tidal sandbank dynamics, we have developed a nonlinear morphodynamic model. A crucial property of the model is that it fully resolves the dynamics on the fast (tidal) timescale, allowing for asymmetric tidal flow with an M0, M2, and M4 component. This approach,

  16. 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.

  17. Dispersion of deep-sea hydrothermal vent effluents and larvae by submesoscale and tidal currents

    Science.gov (United States)

    Vic, Clément; Gula, Jonathan; Roullet, Guillaume; Pradillon, Florence

    2018-03-01

    Deep-sea hydrothermal vents provide sources of geochemical materials that impact the global ocean heat and chemical budgets, and support complex biological communities. Vent effluents and larvae are dispersed and transported long distances by deep ocean currents, but these currents are largely undersampled and little is known about their variability. Submesoscale (0.1-10 km) currents are known to play an important role for the dispersion of biogeochemical materials in the ocean surface layer, but their impact for the dispersion in the deep ocean is unknown. Here, we use a series of nested regional oceanic numerical simulations with increasing resolution (from δx = 6 km to δx = 0.75 km) to investigate the structure and variability of highly-resolved deep currents over the Mid-Atlantic Ridge (MAR) and their role on the dispersion of the Lucky Strike hydrothermal vent effluents and larvae. We shed light on a submesoscale regime of oceanic turbulence over the MAR at 1500 m depth, contrasting with open-ocean - i.e., far from topographic features - regimes of turbulence, dominated by mesoscales. Impacts of submesoscale and tidal currents on larval dispersion and connectivity among vent populations are investigated by releasing neutrally buoyant Lagrangian particles at the Lucky Strike hydrothermal vent. Although the absolute dispersion is overall not sensitive to the model resolution, submesoscale currents are found to significantly increase both the horizontal and vertical relative dispersion of particles at O(1-10) km and O(1-10) days, resulting in an increased mixing of the cloud of particles. A fraction of particles are trapped in submesoscale coherent vortices, which enable transport over long time and distances. Tidal currents and internal tides do not significantly impact the horizontal relative dispersion. However, they roughly double the vertical dispersion. Specifically, particles undergo strong tidally-induced mixing close to rough topographic features

  18. On the tidal interaction of massive extrasolar planets on highly eccentric orbits

    Science.gov (United States)

    Ivanov, P. B.; Papaloizou, J. C. B.

    2004-01-01

    In this paper we develop a theory of disturbances induced by the stellar tidal field in a fully convective slowly rotating planet orbiting on a highly eccentric orbit around a central star. In this case it is appropriate to treat the tidal influence as a succession of impulsive tidal interactions occurring at periastron passage. For a fully convective planet mainly the l= 2 fundamental mode of oscillation is excited. We show that there are two contributions to the mode energy and angular momentum gain due to impulsive tidal interaction: (i) `the quasi-static' contribution, which requires dissipative processes operating in the planet, and (ii) the dynamical contribution associated with excitation of modes of oscillation. These contributions are obtained self-consistently from a single set of the governing equations. We calculate a critical `equilibrium' value of angular velocity of the planet Ωcrit determined by the condition that action of the dynamic tides does not alter the angular velocity at this rotation rate. We show that this can be much larger than the corresponding rate associated with quasi-static tides and that at this angular velocity, the rate of energy exchange is minimized. We also investigate the conditions for the stochastic increase in oscillation energy that may occur if many periastron passages are considered and dissipation is not important. We provide a simple criterion for this instability to occur. Finally, we make some simple estimates of the time-scale of evolution of the orbital semimajor axis and circularization of the initially eccentric orbit due to tides, using a realistic model of the planet and its cooling history, for orbits with periods after circularization typical of those observed for extrasolar planets Pobs>~ 3 d. Quasi-static tides are found to be ineffective for semimajor axes >~0.1 au. On the other hand, dynamic tides could have produced a very large decrease of the semimajor axis of a planet with mass of the order of the

  19. Strategies for the Use of Tidal Stream Currents for Power Generation

    Science.gov (United States)

    Orhan, Kadir; Mayerle, Roberto

    2015-04-01

    Indonesia is one of the priority countries in Southeast Asia for the development of ocean renewable energy facilities and The National Energy Council intends to increase the role of ocean energy significantly in the energy mix for 2010-2050. To this end, the joint German-Indonesian project "Ocean Renewable Energy ORE-12" aims at the identification of marine environments in the Indonesian Archipelago, which are suitable for the efficient generation of electric power by converter facilities. This study, within the ORE-12 project, is focused on the tidal stream currents on the straits between the Indian Ocean and Flores Sea to estimate the energy potentials and to develop strategies for producing renewable energy. FLOW module of Delft3D has been used to run hydrodynamic models for site assessment and design development. In site assessment phase, 2D models have been operated for a-month long periods and with a resolution of 500 m. Later on, in design development phase, detailed 3D models have been developed and operated for three-month long periods and with a resolution of 50 m. Bathymetric data for models have been obtained from the GEBCO_08 Grid and wind data from the Global Forecast System of NOAA's National Climatic Data Center. To set the boundary conditions of models, tidal forcing with 11 harmonic constituents was supplied from TPXO Indian Ocean Atlas (1/12° regional model) and data from HYCOM+NCODA Global 1/12° Analysis have been used to determine salinity and temperature on open boundaries. After the field survey is complete, water level time-series supplied from a tidal gauge located in the domain of interest (8° 20΄ 9.7" S, 122° 54΄ 51.9" E) have been used to verify the models and then energy potentials of the straits have been estimated. As a next step, correspondence between model outputs and measurements taken by the radar system of TerraSAR-X satellite (DLR) will be analysed. Also for the assessment of environmental impacts caused by tidal stream

  20. 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