An integrated model for estimating energy cost of a tidal current turbine farm

International Nuclear Information System (INIS)

Li, Ye; Lence, Barbara J.; Calisal, Sander M.

2011-01-01

A tidal current turbine is a device for harnessing energy from tidal currents and functions in a manner similar to a wind turbine. A tidal current turbine farm consists of a group of tidal current turbines distributed in a site where high-speed current is available. The accurate prediction of energy cost of a tidal current turbine farm is important to the justification of planning and constructing such a farm. However, the existing approaches used to predict energy cost of tidal current turbine farms oversimplify the hydrodynamic interactions between turbines in energy prediction and oversimplify the operation and maintenance strategies involved in cost estimation as well as related fees. In this paper, we develop a model, which integrates a marine hydrodynamic model with high accuracy for predicting energy output and a comprehensive cost-effective operation and maintenance model for estimating the cost that may be incurred in producing the energy, to predict energy cost from a tidal current turbine farm. This model is expected to be able to simulate more complicated cases and generate more accurate results than existing models. As there is no real tidal current turbine farm, we validate this model with offshore wind studies. Finally, case studies about Vancouver are conducted with a scenario-based analysis. We minimize the energy cost by minimizing the total cost and maximizing the total power output under constraints related to the local conditions (e.g., geological and labor information) and the turbine specifications. The results suggest that tidal current energy is about ready to penetrate the electricity market in some major cities in North America if learning curve for the operational and maintenance is minimum. (author)

Coastal Water Quality Modeling in Tidal Lake: Revisited with Groundwater Intrusion

Science.gov (United States)

Kim, C.

2016-12-01

A new method for predicting the temporal and spatial variation of water quality, with accounting for a groundwater effect, has been proposed and applied to a water body partially connected to macro-tidal coastal waters in Korea. The method consists of direct measurement of environmental parameters, and it indirectly incorporates a nutrients budget analysis to estimate the submarine groundwater fluxes. Three-dimensional numerical modeling of water quality has been used with the directly collected data and the indirectly estimated groundwater fluxes. The applied area is Saemangeum tidal lake that is enclosed by 33km-long sea dyke with tidal openings at two water gates. Many investigations of groundwater impact reveal that 10 50% of nutrient loading in coastal waters comes from submarine groundwater, particularly in the macro-tidal flat, as in the west coast of Korea. Long-term monitoring of coastal water quality signals the possibility of groundwater influence on salinity reversal and on the excess mass outbalancing the normal budget in Saemangeum tidal lake. In the present study, we analyze the observed data to examine the influence of submarine groundwater, and then a box model is demonstrated for quantifying the influx and efflux. A three-dimensional numerical model has been applied to reproduce the process of groundwater dispersal and its effect on the water quality of Saemangeum tidal lake. The results show that groundwater influx during the summer monsoon then contributes significantly, 20% more than during dry season, to water quality in the tidal lake.

High-resolution modeling assessment of tidal stream resource in Western Passage of Maine, USA

Science.gov (United States)

Yang, Zhaoqing; Wang, Taiping; Feng, Xi; Xue, Huijie; Kilcher, Levi

2017-04-01

Although significant efforts have been taken to assess the maximum potential of tidal stream energy at system-wide scale, accurate assessment of tidal stream energy resource at project design scale requires detailed hydrodynamic simulations using high-resolution three-dimensional (3-D) numerical models. Extended model validation against high quality measured data is essential to minimize the uncertainties of the resource assessment. Western Passage in the State of Maine in U.S. has been identified as one of the top ranking sites for tidal stream energy development in U.S. coastal waters, based on a number of criteria including tidal power density, market value and transmission distance. This study presents an on-going modeling effort for simulating the tidal hydrodynamics in Western Passage using the 3-D unstructured-grid Finite Volume Community Ocean Model (FVCOM). The model domain covers a large region including the entire the Bay of Fundy with grid resolution varies from 20 m in the Western Passage to approximately 1000 m along the open boundary near the mouth of Bay of Fundy. Preliminary model validation was conducted using existing NOAA measurements within the model domain. Spatial distributions of tidal power density were calculated and extractable tidal energy was estimated using a tidal turbine module embedded in FVCOM under different tidal farm scenarios. Additional field measurements to characterize resource and support model validation were discussed. This study provides an example of high resolution resource assessment based on the guidance recommended by the International Electrotechnical Commission Technical Specification.

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

SPATIAL MOTION OF THE MAGELLANIC CLOUDS: TIDAL MODELS RULED OUT?

International Nuclear Information System (INIS)

Ruzicka, Adam; Palous, Jan; Theis, Christian

2009-01-01

Recently, Kallivayalil et al. derived new values of the proper motion for the Large and Small Magellanic Clouds (LMC and SMC, respectively). The spatial velocities of both Clouds are unexpectedly higher than their previous values resulting from agreement between the available theoretical models of the Magellanic System and the observations of neutral hydrogen (H I) associated with the LMC and the SMC. Such proper motion estimates are likely to be at odds with the scenarios for creation of the large-scale structures in the Magellanic System suggested so far. We investigated this hypothesis for the pure tidal models, as they were the first ones devised to explain the evolution of the Magellanic System, and the tidal stripping is intrinsically involved in every model assuming the gravitational interaction. The parameter space for the Milky Way (MW)-LMC-SMC interaction was analyzed by a robust search algorithm (genetic algorithm) combined with a fast, restricted N-body model of the interaction. Our method extended the known variety of evolutionary scenarios satisfying the observed kinematics and morphology of the Magellanic large-scale structures. Nevertheless, assuming the tidal interaction, no satisfactory reproduction of the H I data available for the Magellanic Clouds was achieved with the new proper motions. We conclude that for the proper motion data by Kallivayalil et al., within their 1σ errors, the dynamical evolution of the Magellanic System with the currently accepted total mass of the MW cannot be explained in the framework of pure tidal models. The optimal value for the western component of the LMC proper motion was found to be μ W lmc ∼> -1.3 mas yr -1 in case of tidal models. It corresponds to the reduction of the Kallivayalil et al. value for μ W lmc by ∼ 40% in its magnitude.

Hydrodynamic modelling of tidal inlets in Hue, Vietnam

NARCIS (Netherlands)

Lam, N.T.; Verhagen, H.J.; Van der Wegen, M.

2003-01-01

Application of an one-dimensional numerical model for hydrodynamic simulation of a complex lagooninlet system in Vietnam is presented. Model results help to get a better understanding on the behaviour of the system. Based on the numerical model results and analytic solutions, stability of tidal

The rotation and fracture history of Europa from modeling of tidal-tectonic processes

Science.gov (United States)

Rhoden, Alyssa Rose

Europa's surface displays a complex history of tectonic activity, much of which has been linked to tidal stress caused by Europa's eccentric orbit and possibly non-synchronous rotation of the ice shell. Cycloids are arcuate features thought to have formed in response to tidal normal stress while strike-slip motion along preexisting faults has been attributed to tidal shear stress. Tectonic features thus provide constraints on the rotational parameters that govern tidal stress, and can help us develop an understanding of the tidal-tectonic processes operating on ice covered ocean moons. In the first part of this work (Chapter 3), I test tidal models that include obliquity, fast precession, stress due to non-synchronous rotation (NSR), and physical libration by comparing how well each model reproduces observed cycloids. To do this, I have designed and implemented an automated parameter-searching algorithm that relies on a quantitative measure of fit quality to identify the best fits to observed cycloids. I apply statistical techniques to determine the tidal model best supported by the data and constrain the values of Europa's rotational parameters. Cycloids indicate a time-varying obliquity of about 1° and a physical libration in phase with the eccentricity libration, with amplitude >1°. To obtain good fits, cycloids must be translated in longitude, which implies non-synchronous rotation of the icy shell. However, stress from NSR is not well-supported, indicating that the rotation rate is slow enough that these stresses relax. I build upon the results of cycloid modeling in the second section by applying calculations of tidal stress that include obliquity to the formation of strike-slip faults. I predict the slip directions of faults with the standard formation model---tidal walking (Chapter 5)---and with a new mechanical model I have developed, called shell tectonics (Chapter 6). The shell tectonics model incorporates linear elasticity to determine slip and stress

Development of a model counter-rotating type horizontal-axis tidal turbine

Science.gov (United States)

Huang, B.; Yoshida, K.; Kanemoto, T.

2016-05-01

In the past decade, the tidal energies have caused worldwide concern as it can provide regular and predictable renewable energy resource for power generation. The majority of technologies for exploiting the tidal stream energy are based on the concept of the horizontal axis tidal turbine (HATT). A unique counter-rotating type HATT was proposed in the present work. The original blade profiles were designed according to the developed blade element momentum theory (BEMT). CFD simulations and experimental tests were adopted to the performance of the model counter-rotating type HATT. The experimental data provides an evidence of validation of the CFD model. Further optimization of the blade profiles was also carried out based on the CFD results.

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.

A life-cycle model for wave-dominated tidal inlets along passive margin coasts of North America

Science.gov (United States)

Seminack, Christopher T.; McBride, Randolph A.

2018-03-01

A regional overview of 107 wave-dominated tidal inlets along the U.S. Atlantic coast, U.S. Gulf of Mexico coast, and Canadian Gulf of St. Lawrence coast yielded a generalized wave-dominated tidal inlet life-cycle model that recognized the rotational nature of tidal inlets. Tidal inlets are influenced by concurrently acting processes transpiring over two timescales: short-term, event-driven processes and long-term, evolutionary processes. Wave-dominated tidal inlets are classified into three rotational categories based on net longshore sediment transport direction and rotation direction along the landward (back-barrier) portion of the inlet channel: downdrift channel rotation, updrift channel rotation, or little-to-no channel rotation. Lateral shifting of the flood-tidal delta depocenter in response to available estuarine accommodation space appears to control inlet channel rotation. Flood-tidal delta deposits fill accommodation space locally within the estuary (i.e., creating bathymetric highs), causing the tidal-inlet channel to rotate. External influences, such as fluvial discharge, pre-existing back-barrier channels, and impeding salt marsh will also influence inlet-channel rotation. Storm events may rejuvenate the tidal inlet by scouring sediment within the flood-tidal delta, increasing local accommodation space. Wave-dominated tidal inlets are generally unstable and tend to open, concurrently migrate laterally and rotate, infill, and close. Channel rotation is a primary reason for wave-dominated tidal inlet closure. During rotation, the inlet channel lengthens and hydraulic efficiency decreases, thus causing tidal prism to decrease. Tidal prism, estuarine accommodation space, and sediment supply to the flood-tidal delta are the primary variables responsible for tidal inlet rotation. Stability of wave-dominated tidal inlets is further explained by: stability (S) = tidal prism (Ω) + estuarine accommodation space (V) - volume of annual sediment supply (Mt

Impact of intertidal area characteristics on estuarine tidal hydrodynamics: A modelling study for the Scheldt Estuary

Science.gov (United States)

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

2017-11-01

Marsh restoration projects are nowadays being implemented as ecosystem-based strategies to reduce flood risks and to restore intertidal habitat along estuaries. Changes in estuarine tidal hydrodynamics are expected along with such intertidal area changes. A validated hydrodynamic model of the Scheldt Estuary is used to gain fundamental insights in the role of intertidal area characteristics on tidal hydrodynamics and tidal asymmetry in particular through several geomorphological scenarios in which intertidal area elevation and location along the estuary is varied. Model results indicate that the location of intertidal areas and their storage volume relative to the local tidal prism determine the intensity and reach along the estuary over which tidal hydrodynamics are affected. Our model results also suggest that intertidal storage areas that are located within the main estuarine channel system, and hence are part of the flow-carrying part of the estuary, may affect tidal hydrodynamics differently than intertidal areas that are side-basins of the main estuarine channel, and hence only contribute little to the flow-carrying cross-section of the estuary. If tidal flats contribute to the channel cross-section and exert frictional effects on the tidal propagation, the elevation of intertidal flats influences the magnitude and direction of tidal asymmetry along estuarine channels. Ebb-dominance is most strongly enhanced if tidal flats are around mean sea level or slightly above. Conversely, flood-dominance is enhanced if the tidal flats are situated low in the tidal frame. For intertidal storage areas at specific locations besides the main channel, flood-dominance in the estuary channel peaks in the vicinity of those areas and generally reduces upstream and downstream compared to a reference scenario. Finally, the model results indicate an along-estuary varying impact on the tidal prism as a result of adding intertidal storage at a specific location. In addition to known

A Tidally Averaged Sediment-Transport Model for San Francisco Bay, California

Science.gov (United States)

Lionberger, Megan A.; Schoellhamer, David H.

2009-01-01

A tidally averaged sediment-transport model of San Francisco Bay was incorporated into a tidally averaged salinity box model previously developed and calibrated using salinity, a conservative tracer (Uncles and Peterson, 1995; Knowles, 1996). The Bay is represented in the model by 50 segments composed of two layers: one representing the channel (>5-meter depth) and the other the shallows (0- to 5-meter depth). Calculations are made using a daily time step and simulations can be made on the decadal time scale. The sediment-transport model includes an erosion-deposition algorithm, a bed-sediment algorithm, and sediment boundary conditions. Erosion and deposition of bed sediments are calculated explicitly, and suspended sediment is transported by implicitly solving the advection-dispersion equation. The bed-sediment model simulates the increase in bed strength with depth, owing to consolidation of fine sediments that make up San Francisco Bay mud. The model is calibrated to either net sedimentation calculated from bathymetric-change data or measured suspended-sediment concentration. Specified boundary conditions are the tributary fluxes of suspended sediment and suspended-sediment concentration in the Pacific Ocean. Results of model calibration and validation show that the model simulates the trends in suspended-sediment concentration associated with tidal fluctuations, residual velocity, and wind stress well, although the spring neap tidal suspended-sediment concentration variability was consistently underestimated. Model validation also showed poor simulation of seasonal sediment pulses from the Sacramento-San Joaquin River Delta at Point San Pablo because the pulses enter the Bay over only a few days and the fate of the pulses is determined by intra-tidal deposition and resuspension that are not included in this tidally averaged model. The model was calibrated to net-basin sedimentation to calculate budgets of sediment and sediment-associated contaminants. While

Numerical modelling of tides and tidal currents in the Gulf of Kutch

Digital Repository Service at National Institute of Oceanography (India)

Unnikrishnan, A.S.

An application of a two-dimensional tidal model to study the tidal regime in the Gulf of Kutch is made. This is with a view to synthesise various information on tides and currents that are available in the Gulf. A comparison of surface elevations...

On the Tidal Evolution of the Earth-Moon System: A Cosmological Model

Directory of Open Access Journals (Sweden)

Arbab A. I.

2009-01-01

Full Text Available We have presented a cosmological model for the tidal evolution of the Earth-Moon system. We have found that the expansion of the universe has immense consequences on our local systems. The model can be compared with the present observational data. The close approach problem inflicting the known tidal theory is averted in this model. We have also shown that the astronomical and geological changes of our local systems are of the order of Hubble constant.

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.

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.

Thermal tides and studies to tune the mechanistic tidal model using UARS observations

Directory of Open Access Journals (Sweden)

V. A. Yudin

1997-09-01

Full Text Available Monthly simulations of the thermal diurnal and semidiurnal tides are compared to High-Resolution Doppler Imager (HRDI and Wind Imaging Interferometer (WINDII wind and temperature measurements on the Upper-Atmosphere Research Satellite (UARS. There is encouraging agreement between the observations and the linear global mechanistic tidal model results both for the diurnal and semidiurnal components in the equatorial and mid-latitude regions. This gives us the confidence to outline the first steps of an assimilative analysis/interpretation for tides, dissipation, and mean flow using a combination of model results and the global measurements from HRDI and WINDII. The sensitivity of the proposed technique to the initial guess employed to obtain a best fit to the data by tuning model parameters is discussed for the January and March 1993 cases, when the WINDII day and night measurements of the meridional winds between 90 and 110 km are used along with the daytime HRDI measurements. Several examples for the derivation of the tidal variables and decomposition of the measured winds into tidal and mean flow components using this approach are compared with previous tidal estimates and modeling results for the migrating tides. The seasonal cycle of the derived diurnal tidal amplitudes are discussed and compared with radar observation between 80 and 100 km and 40°S and 40°N.

Thermal tides and studies to tune the mechanistic tidal model using UARS observations

Directory of Open Access Journals (Sweden)

V. A. Yudin

Full Text Available Monthly simulations of the thermal diurnal and semidiurnal tides are compared to High-Resolution Doppler Imager (HRDI and Wind Imaging Interferometer (WINDII wind and temperature measurements on the Upper-Atmosphere Research Satellite (UARS. There is encouraging agreement between the observations and the linear global mechanistic tidal model results both for the diurnal and semidiurnal components in the equatorial and mid-latitude regions. This gives us the confidence to outline the first steps of an assimilative analysis/interpretation for tides, dissipation, and mean flow using a combination of model results and the global measurements from HRDI and WINDII. The sensitivity of the proposed technique to the initial guess employed to obtain a best fit to the data by tuning model parameters is discussed for the January and March 1993 cases, when the WINDII day and night measurements of the meridional winds between 90 and 110 km are used along with the daytime HRDI measurements. Several examples for the derivation of the tidal variables and decomposition of the measured winds into tidal and mean flow components using this approach are compared with previous tidal estimates and modeling results for the migrating tides. The seasonal cycle of the derived diurnal tidal amplitudes are discussed and compared with radar observation between 80 and 100 km and 40^°S and 40^°N.

Modeling Evaluation of Tidal Stream Energy and the Impacts of Energy Extraction on Hydrodynamics in the Taiwan Strait

Directory of Open Access Journals (Sweden)

Ming-Hsi Hsu

2013-04-01

Full Text Available Tidal stream speeds in straits are accelerated because of geographic and bathymetric features. For instance, narrow channels and shallows can cause high tidal stream energy. In this study, water level and tidal current were simulated using a three-dimensional semi-implicit Eulerian-Lagrangian finite-element model to investigate the complex tidal characteristics in the Taiwan Strait and to determine potential locations for harnessing tidal stream energy. The model was driven by nine tidal components (M2, S2, N2, K2, K1, O1, P1, Q1, and M4 at open boundaries. The modeling results were validated with the measured data, including water level and tidal current. Through the model simulations, we found that the highest tidal currents occurred at the Penghu Channel in the Taiwan Strait. The Penghu Channel is an appropriate location for the deployment of a tidal turbine array because of its deep and flat bathymetry. The impacts of energy extraction on hydrodynamics were assessed by considering the momentum sink approach. The simulated results indicate that only minimal impacts would occur on water level and tidal current in the Taiwan Strait if a turbine array (55 turbines was installed in the Penghu Channel.

The northern tidal dynamic of Aceh waters: A 3D numerical model

Science.gov (United States)

Irham, M.; Miswar, E.; Ilhamsyah, Y.; Setiawan, I.

2018-05-01

The northern tidal dynamic of Aceh waters studied by employing three-dimensional (3D) numerical hydrodynamic model. The purpose of this study is to understand the phenomena and the characteristic of the northern tidal dynamic of Aceh waters. The research used the explicit-splitting scheme numerical model of Navier-Stokes formulation. The result displays that the vertical rotation of flow movement (vertical eddy) at a depth of 15 to 25 meter eastern part of the study area. Hence, the result also informs that the current circulation identically to the upwelling in the western region of Aceh during the wet season and vice versa. However, during the transitional season, the flow circulation depends on how the tidal dynamic occurs in the area.

Modelling of the impact of biofouling on hydrodynamics downstream of a tidal turbine

Science.gov (United States)

Bennis, A. C.; Rivier, A.; Dauvin, J. C.

2016-02-01

Biological organisms, like barnacles, mussels or bryozoans, colonize rapidly an immersed surface and could form a thickness until several centimeters on it. This biofouling could modify hydrodynamics around tidal turbine by increasing drag and hence resistance and could be detrimental to the performance of turbine (e.g. Orme et al., 2001; Khor and Xiao, 2011). Our work focuses on modifications of vortices downstream of a tidal turbine due to biofouling using CFD. Fixed biological organisms are solved explicitly by the model and are considered by modifying the blade profile. Firstly an airfoil colonized by barnacles is modelled for various fouling height and spacing and results are compared to experimental and simulated data (Orme et al., 2001; Khor and Xiao, 2011) in order to assess the capacity of the model to reproduce the flow around a blade with biofouling. Then a Darrieus vertical axis tidal turbine is modelled using a dynamic mesh. Configuration with smooth clean blades is assessed by comparison with experiments and simulations made by Roa (2011) and Bossard (2012). Biological organisms with various heights, spacing and shapes are fixed on blades and wakes downstream of clean and colonized tidal turbine are compared. Vorticity fields around the tidal turbine are clearly modified when blades are colonized. Samples will be taken from location where farms are planned to be built (Alderney Race/Raz Blanchard) to characterize more precisely the characteristics of species which are liable to fix on tidal turbine.Reference:Bossard (2012). Doctoral dissertation, Université de Grenoble.Khor & Xiao. (2011). Ocean Eng, 38(10), 1065-1079. Orme et al. (2001). Marine Renewable Energy Conference, Newcastle.Roa (2011).Doctoral dissertation, Université de Grenoble.

Observations and models of star formation in the tidal features of interacting galaxies

International Nuclear Information System (INIS)

Wallin, J.F.; Schombert, J.M.; Struck-Marcell, C.

1990-01-01

Multi-color surface photometry (BVri) is presented for the tidal features in a sample of interacting galaxies. Large color variations are found between the morphological components and within the individual components. The blue colors in the primary and the tidal features are most dramatic in B-V, and not in V-i, indicating that star formation instead of metallicity or age dominates the colors. Color variations between components is larger in systems shortly after interaction begins and diminishes to a very low level in systems which are merged. Photometric models for interacting systems are presented which suggest that a weak burst of star formation in the tidal features could cause the observed color distributions. Dynamical models indicate that compression occurs during the development of tidal features causing an increase in the local density by a factor of between 1.5 and 5. Assuming this density increase can be related to the star formation rate by a Schmidt law, the density increases observed in the dynamical models may be responsible for the variations in color seen in some of the interacting systems. Limitations of the dynamical models are also discussed

Tides in the Last Interglacial: insights from notch geometry and palaeo tidal models in Bonaire, Netherland Antilles.

Science.gov (United States)

Lorscheid, Thomas; Felis, Thomas; Stocchi, Paolo; Obert, J Christina; Scholz, Denis; Rovere, Alessio

2017-11-24

The study of past sea levels relies largely on the interpretation of sea-level indicators. Palaeo tidal notches are considered as one of the most precise sea-level indicators as their formation is closely tied to the local tidal range. We present geometric measurements of modern and palaeo (Marine Isotope Stage (MIS) 5e) tidal notches on Bonaire (southern Caribbean Sea) and results from two tidal simulations, using the present-day bathymetry and a palaeo-bathymetry. We use these two tools to investigate changes in the tidal range since MIS 5e. Our models show that the tidal range changes most significantly in shallow areas, whereas both, notch geometry and models results, suggest that steeper continental shelves, such as the ones bordering the island of Bonaire, are less affected to changes in tidal range in conditions of MIS 5e sea levels. We use our data and results to discuss the importance of considering changes in tidal range while reconstructing MIS 5e sea level histories, and we remark that it is possible to use hydrodynamic modelling and notch geometry as first-order proxies to assess whether, in a particular area, tidal range might have been different in MIS 5e with respect to today.

Plant distributions along salinity and tidal gradients in Oregon tidal marshes

Science.gov (United States)

Accurately modeling climate change effects on tidal marshes in the Pacific Northwest requires understanding how plant assemblages and species are presently distributed along gradients of salinity and tidal inundation. We outline on-going field efforts by the EPA and USGS to dete...

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

Tidal eddies in a semi-enclosed basin: A model study

Digital Repository Service at National Institute of Oceanography (India)

Vethamony, P.; Reddy, G.S.; Babu, M.T.; Desa, E.; Sudheesh, K.

A modeling study has been carried out to support a Marine Management Plan for the Gulf of Kachchh, India and here the hydrodynamic part of the programme is described. The hydrodynamic model accurately predicts the tides and tidal currents present...

Sensitivity of tidal sand wave characteristics to environmental parameters: A combined data analysis and modelling approach

NARCIS (Netherlands)

van Santen, R.B.; de Swart, H.E.; van Dijk, T.A.G.P.

2011-01-01

An integrated field data-modelling approach is employed to investigate relationships between the wavelength of tidal sand waves and four environmental parameters: tidal current amplitude, water depth, tidal ellipticity and median grain size. From echo sounder data at 23 locations on the Dutch

Modelling the impacts of sea level rise on tidal basin ecomorphodynamics and mangrove habitat evolution

Science.gov (United States)

van Maanen, Barend; Coco, Giovanni; Bryan, Karin

2016-04-01

The evolution of tidal basins and estuaries in tropical and subtropical regions is often influenced by the presence of mangrove forests. These forests are amongst the most productive environments in the world and provide important ecosystem services. However, these intertidal habitats are also extremely vulnerable and are threatened by climate change impacts such as sea level rise. It is therefore of key importance to improve our understanding of how tidal systems occupied by mangrove vegetation respond to rising water levels. An ecomorphodynamic model was developed that simulates morphological change and mangrove forest evolution as a result of mutual feedbacks between physical and biological processes. 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. Under stable water levels, model results indicate that mangrove trees 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 landward expansion of the channels, on the other hand, is reduced. Model simulations including sea level rise suggest that mangroves can potentially enhance the ability of the soil surface to maintain an elevation within the upper portion of the intertidal zone. While the sea level is rising, mangroves are migrating landward and the channel network tends to expand landward too. The presence of mangrove trees, however, was found to hinder both the branching and headward erosion of the landward expanding channels. Simulations are performed according to different sea level rise scenarios and with different tidal range conditions to assess which tidal environments are most vulnerable. Changes in the properties of the tidal channel networks are being examined as well. Overall, model results highlight the role of mangroves in driving the

Modeling Interactions between Backbarrier Marshes, Tidal Inlets, Ebb-deltas, and Adjacent Barriers Exposed to Rising Sea Levels

Science.gov (United States)

Hanegan, K.; Georgiou, I. Y.; FitzGerald, D.

2016-02-01

Along barrier island chains, tidal exchange between the backbarrier and the coastal ocean supports unique saltwater and brackish ecosystems and is responsible for exporting sediment and nutrients to the surrounding coast. Tidal prism, basement controls, and wave and tidal energy dictate the size and number of tidal inlets and the volume of sand sequestered in ebb-tidal deltas. The inlet tidal prism is a function of bay area, tidal range, and secondary controls, including flow inertia, basinal hypsometry, and frictional factors. Sea- level rise (SLR) is threatening coastal environments, causing mainland flooding, changes in sediment supply, and conversion of wetlands and tidal flats to open water. These factors are impacting basinal hypsometry and increasing open water area, resulting in enlarging tidal prisms, increased dimensions of tidal inlets and ebb-tidal deltas, and erosion along adjacent barrier shorelines. Although the effects of SLR on coastal morphology are difficult to study by field observations alone, physics-based numerical models provide a sophisticated means of analyzing coastal processes over decadal time-scales and linking process causation to long term development. Here, we use a numerical model that includes relevant features in the barrier/tidal basin system, linking back-barrier marsh degradation, inlet expansion, and ebb-delta growth to barrier erosion through long-term hydrodynamic and morphology simulations. Sediment exchange and process interactions are investigated using an idealized domain resembling backbarrier basins of mixed energy coasts so that the sensitivity to varying SLR rates, interior marsh loss, sediment supply, and hydrodynamic controls can be more easily analyzed. Model runs explore these processes over geologic time scales, demonstrating the vulnerability of backbarrier systems to projected SLR and marsh loss. Results demonstrate the links between changing basin morphology and shoreface sedimentation patterns that initiate

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.

A coupled geomorphic and ecological model of tidal marsh evolution.

Science.gov (United States)

Kirwan, Matthew L; Murray, A Brad

2007-04-10

The evolution of tidal marsh platforms and interwoven channel networks cannot be addressed without treating the two-way interactions that link biological and physical processes. We have developed a 3D model of tidal marsh accretion and channel network development that couples physical sediment transport processes with vegetation biomass productivity. Tidal flow tends to cause erosion, whereas vegetation biomass, a function of bed surface depth below high tide, influences the rate of sediment deposition and slope-driven transport processes such as creek bank slumping. With a steady, moderate rise in sea level, the model builds a marsh platform and channel network with accretion rates everywhere equal to the rate of sea-level rise, meaning water depths and biological productivity remain temporally constant. An increase in the rate of sea-level rise, or a reduction in sediment supply, causes marsh-surface depths, biomass productivity, and deposition rates to increase while simultaneously causing the channel network to expand. Vegetation on the marsh platform can promote a metastable equilibrium where the platform maintains elevation relative to a rapidly rising sea level, although disturbance to vegetation could cause irreversible loss of marsh habitat.

Modeling tides and vertical tidal mixing: A reality check

International Nuclear Information System (INIS)

Robertson, Robin

2010-01-01

Recently, there has been a great interest in the tidal contribution to vertical mixing in the ocean. In models, vertical mixing is estimated using parameterization of the sub-grid scale processes. Estimates of the vertical mixing varied widely depending on which vertical mixing parameterization was used. This study investigated the performance of ten different vertical mixing parameterizations in a terrain-following ocean model when simulating internal tides. The vertical mixing parameterization was found to have minor effects on the velocity fields at the tidal frequencies, but large effects on the estimates of vertical diffusivity of temperature. Although there was no definitive best performer for the vertical mixing parameterization, several parameterizations were eliminated based on comparison of the vertical diffusivity estimates with observations. The best performers were the new generic coefficients for the generic length scale schemes and Mellor-Yamada's 2.5 level closure scheme.

Seepage Flow Model and Deformation Properties of Coastal Deep Foundation Pit under Tidal Influence

Directory of Open Access Journals (Sweden)

Shu-chen Li

2018-01-01

Full Text Available As the coastal region is the most developed region in China, an increasing number of engineering projects are under construction in it in recent years. However, the quality of these projects is significantly affected by groundwater, which is influenced by tidal variations. Therefore, the regional groundwater dynamic characteristics under tidal impact and the spatiotemporal evolution of the seepage field must be considered in the construction of the projects. Then, Boussinesq function was introduced into the research to deduce the seepage equation under tidal influence for the coastal area. To determine the spatiotemporal evolution of the deep foundation pit seepage field and the coastal seepage field evolution model, numerical calculations based on changes in the tidal water level and seepage equation were performed using MATLAB. According to the developed model, the influence of the seepage field on the foundation pit supporting structure in the excavation process was analyzed through numerical simulations. The results of this research could be considered in design and engineering practice.

Challenges in the modeling of tidal disruption events lightcurves

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Lodato G.

2012-12-01

Full Text Available In this contribution, I review the recent developments on the modeling of the lightcurve of tidal disruption events. Our understanding has evolved significantly from the earlier seminal results that imply a simple power-law decay of the bolometric light curve as t−5/3. We now know that the details of the rise to the peak of the lightcurve is determined mainly by the internal structure of the disrupted star. We also have improved models for the disc thermal emission, showing that in this case the decline of the luminosity with time should be much flatter than the standard t−5/3 law, especially in optical and UV wavelengths, while the X-ray lightcurve is generally best suited to track the bolometric one. Finally, we are just starting to explore the interesting general relativistic effects that might arise for such events, for which the tidal radius lies very close to the black hole event horizon.

Tidally Heated Terrestrial Exoplanets

Science.gov (United States)

Henning, Wade Garrett

This work models the surface and internal temperatures for hypothetical terrestrial planets in situations involving extreme tidal heating. The feasibility of such planets is evaluated in terms of the orbital perturbations that may give rise to them, their required proximity to a hoststar, and the potential for the input tidal heating to cause significant partial melting of the mantle. Trapping terrestrial planets into 2:1 resonances with migrating Hot Jupiters is considered as a reasonable way for Earth-like worlds to both maintain high eccentricities and to move to short enough orbital periods (1-20 days) for extreme tidal heating to occur. Secular resonance and secular orbital perturbations may support moderate tidal heating at a low equilibrium eccentricity. At orbital periods below 10-30 days, with eccentricities from 0.01 to 0.1, tidal heat may greatly exceed radiogenic heat production. It is unlikely to exceed insolation, except when orbiting very low luminosity hosts, and thus will have limited surface temperature expression. Observations of such bodies many not be able to detect tidal surface enhancements given a few percent uncertainty in albedo, except on the nightside of spin synchronous airless objects. Otherwise detection may occur via spectral detection of hotspots or high volcanic gas concentrations including sulfur dioxide and hydrogen sulfide. The most extreme cases may be able to produce magma oceans, or magma slush mantles with up to 40-60% melt fractions. Tides may alter the habitable zones for smaller red dwarf stars, but are generally detrimental. Multiple viscoelastic models, including the Maxwell, Voigt-Kelvin, Standard Anelastic Solid, and Burgers rheologies are explored and applied to objects such as Io and the super-Earth planet GJ 876d. The complex valued Love number for the Burgers rheology is derived and found to be a useful improvement when modeling the low temperature behavior of tidal bodies, particularly during low eccentricity

Use of Roche coordinates in the problems of small oscillations of tidally-distorted stellar models. II

International Nuclear Information System (INIS)

Mohan, C.; Singh, V.P.

1979-01-01

Kopal's method of Roche coordinates used by the authors in an earlier paper (Mohan and Singh, 1978) to study the problems of small oscillations of tidally-distorted stars has been extended further to take into account the effect of second-order terms in tidal distortion. The results show that the effect of including terms of second order of smallness in tidal distortion in the metric coefficients of the Roche coordinates of tidally distroted stars is quite significant, especially in case of stars with extended envelopes and (or) larger values of the companion star producing tidal distortion. Some of the models which were earlier found stable against small perturbations now become dynamically unstable with the inclusion of the terms of second order of smallness in tidal effects. (Auth.)

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

Phase lag control of tidally reversing mega-ripple geometry and bed stress in tidal inlets

Science.gov (United States)

Traykovski, P.

2016-02-01

Recent observations in the Columbia River Mouth, New River Inlet, and Wasque Shoals have shown that tidally reversing mega-ripples are an ubiquitous bedform morphology in energetic tidal inlets. As the name implies, these bedforms reverse asymmetry and migration direction in each half tidal cycle. With wavelengths of 2 to 5 m and heights of 0.2 to 0.5 m, these bedforms are larger than current formed ripples, but smaller than dunes. Unlike dunes which have a depth dependent geometry, observations indicate the tidally reversing mega-ripples geometry is related to the time dependent tidal flow and independent of depth. Previous empirical relations for predicting the geometry of ripples or dunes do not successfully predict the geometry of these features. A time dependent geometric model was developed that accounts for the reversal of migration and asymmetry to successfully predict bedform geometry. The model requires sufficient sediment transport in each half tidal cycle to reverse the asymmetry before the bedforms begin to grow. Both the observations and model indicate that the complete reversal of asymmetry and development of a steep lee face occurs near or after maximum flow in each half tidal cycle. This phase lag in bedform response to tidal forcing also has important implications for bed stress in tidal inlets. Observations of frictional drag in the Columbia River mouth based on a tidal momentum balance of surface slope over 10 km regressed against quadratic near bed velocity show drag coefficients that fall off as CD U-1.4. Reynolds stress measurements performed using the dual ADV differencing technique show similar relations. The Reynolds stress measurements also show a dramatic asymmetry between accelerating flows and decelerating flows with a factor of 5 increase during deceleration. Pulse coherent Doppler profiles of near bed turbulence indicate that the turbulence is dominated by energetic fluctuations in separation zones downstream of steep lee faces. The

The origin of neap-spring tidal cycles

Science.gov (United States)

Kvale, E.P.

2006-01-01

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

A modeling approach to establish environmental flow threshold in ungauged semidiurnal tidal river

Science.gov (United States)

Akter, A.; Tanim, A. H.

2018-03-01

Due to shortage of flow monitoring data in ungauged semidiurnal river, 'environmental flow' (EF) determination based on its key component 'minimum low flow' is always difficult. For EF assessment this study selected a reach immediately after the Halda-Karnafuli confluence, a unique breeding ground for Indian Carp fishes of Bangladesh. As part of an ungauged tidal river, EF threshold establishment faces challenges in changing ecological paradigms with periodic change of tides and hydrologic alterations. This study describes a novel approach through modeling framework comprising hydrological, hydrodynamic and habitat simulation model. The EF establishment was conceptualized according to the hydrologic process of an ungauged semi-diurnal tidal regime in four steps. Initially, a hydrologic model coupled with a hydrodynamic model to simulate flow considering land use changes effect on streamflow, seepage loss of channel, friction dominated tidal decay as well as lack of long term flow characteristics. Secondly, to define hydraulic habitat feature, a statistical analysis on derived flow data was performed to identify 'habitat suitability'. Thirdly, to observe the ecological habitat behavior based on the identified hydrologic alteration, hydraulic habitat features were investigated. Finally, based on the combined habitat suitability index flow alteration and ecological response relationship was established. Then, the obtained EF provides a set of low flow indices of desired regime and thus the obtained discharge against maximum Weighted Usable Area (WUA) was defined as EF threshold for the selected reach. A suitable EF regime condition was obtained within flow range 25-30.1 m3/s i.e., around 10-12% of the mean annual runoff of 245 m3/s and these findings are within researchers' recommendation of minimum flow requirement. Additionally it was observed that tidal characteristics are dominant process in semi-diurnal regime. However, during the study period (2010-2015) the

Comparison of actual tidal volume in neonatal lung model volume control ventilation using three ventilators.

Science.gov (United States)

Toyama, H; Endo, Y; Ejima, Y; Matsubara, M; Kurosawa, S

2011-07-01

In neonates, small changes in tidal volumes (V(T)) may lead to complications. Previous studies have shown a significant difference between ventilator-measured tidal volume and tidal volume delivered (actual V(T)). We evaluated the accuracy of three different ventilators to deliver small V(T) during volume-controlled ventilation. We tested Servo 300, 840 ventilator and Evita 4 Neoflow ventilators with lung models simulating normal and injured neonatal lung compliance models. Gas volume delivered from the ventilator into the test circuit (V(TV)) and actual V(T) to the test lung were measured using Ventrak respiration monitors at set V(T) (30 ml). The gas volume increase of the breathing circuit was then calculated. Tidal volumes of the SV300 and PB840 in both lung models were similar to the set V(T) and the actual tidal volumes in the injured model (20.7 ml and 19.8 ml, respectively) were significantly less than that in the normal model (27.4 ml and 23.4 ml). PB840 with circuit compliance compensation could not improve the actual V(T). V(TV) of the EV4N in the normal and the injured models (37.8 ml and 46.6 ml) were markedly increased compared with set V(T), and actual V(T) were similar to set V(T) in the normal and injured model (30.2 ml and 31.9 ml, respectively). EV4N measuring V(T) close to the lung could match actual V(T) to almost the same value as the set V(T) however the gas volume of the breathing circuit was increased. If an accurate value for the patient's actual V(T) is needed, this V(T) must be measured by a sensor located between the Y-piece and the tracheal tube.

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

Tidal propagation off the central west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Unnikrishnan, A.S.

. [Keywords: Tidal propagation, Mumbai high, Global tidal model, Shelf model, Central west coast of India] Introduction In coastal regions, tides play an important role in determining circulation and hydrography. Barotropic tides coming from the open... with increase in the width of the shelf. Materials and Methods Global tidal models Schwiderski5 used a hydrodynamic interpolation technique to determine the amplitude and phase of tidal constituents of global ocean. Since the availability of satellite...

A Double Zone Dynamical Model For The Tidal Evolution Of The Obliquity

Science.gov (United States)

Damiani, Cilia

2017-10-01

It is debated wether close-in giants planets can form in-situ and if not, which mechanisms are responsible for their migration. One of the observable tests for migration theories is the current value of the obliquity. But after the main migration mechanism has ended, the combined effects of tidal dissipation and the magnetic braking of the star lead to the evolution of both the obliquity and the semi-major axis. The observed correlation between effective temperature and measured projected obliquity has been taken as evidence of such mechanisms being at play. Here I present an improved model for the tidal evolution of the obliquity. It includes all the components of the dynamical tide for circular misaligned systems. It uses an analytical formulation for the frequency-averaged dissipation for each mode, depending only on global stellar parameters, giving a measure of the dissipative properties of the convective zone of the host as it evolves in time. The model also includes the effect of magnetic braking in the framework of the double zone model. This results in the estimation of different tidal evolution timescales for the evolution of the planet's semi-major axis and obliquity depending on the properties of the stellar host. This model can be used to test migration theories, provided that a good determination of stellar radii, masses and ages can be obtained.

Modeling effects of secondary tidal basins on estuarine morphodynamics

Science.gov (United States)

Nnafie, Abdel; Van Oyen, Tomas; De Maerschalck, Bart

2017-04-01

Many estuaries are situated in very densely populated areas with high economic activities that often conflict with their ecological values. For centuries, geometry and bathymetry of estuaries have been drastically modified trough engineering works such as embanking, sand extraction, channel deepening, land reclamations, etc. It is generally recognized that these works may increase the tidal range (e.g., Scheldt, Ems, Elbe) and turbidity (e.g., Loire, Ems) in estuaries [cf. Kerner, 2007; Wang et al., 2009; Winterwerp and Wang, 2013; Van Maren et al., 2015b,a]. In recent years, construction of secondary basins (also called retention basins) has gained increasing popularity among coastal managers to reduce tidal range and turbidity [Donner et al., 2012]. Previous studies have shown that location, geometry and number of secondary basins have a significant impact on tidal characteristics and sediment transport [Alebregtse and de Swart, 2014; Roos and Schuttelaars, 2015]. However, knowledge on how these secondary basins affect the morphodynamic development of estuaries on long time scales (order decades to centuries) is still lacking. The specific objectives of this study are twofold. First, to investigate effects of secondary basins on the long-term morphodynamic evolution of estuaries. In particular, effects of the presence of such a basin on the morphodynamic evolution of the main channel in the estuary and the physics underlying channel migration will be examined. For this, the Western Scheldt estuary (situated in the Netherlands) is used as a case study, which used to consist of multiple secondary tidal basins that were located at different positions in the estuary, and which have been gradually closed off between 1800 and 1968. Second, to systematically quantify sensitivity of model results to location, geometry, and to number of secondary basins. To this end, the state-of-the- art numerical model Delft3D is used, which has been successfully applied to

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.

Model documentation of assessment and nursing diagnosis in the practice of nursing care management for nursing students

OpenAIRE

A. Aziz Alimul Hidayat; M. Kes

2015-01-01

Model documentation of assessment and nursing diagnosis in the practice of nursing care management is an integration model in nursing care records, especially records nursing assessment and diagnosis in one format. This model can reduce the duration of the recording in nursing care, and make it easier for students to understand the nursing diagnosis, so that nursing interventions more effective. The purpose of this paper was to describes the form integration documentation of nursing assessmen...

The role of bank collapse on tidal creek ontogeny: A novel process-based model for bank retreat

Science.gov (United States)

Gong, Zheng; Zhao, Kun; Zhang, Changkuan; Dai, Weiqi; Coco, Giovanni; Zhou, Zeng

2018-06-01

Bank retreat in coastal tidal flats plays a primary role on the planimetric shape of tidal creeks and is commonly driven by both flow-induced bank erosion and gravity-induced bank collapse. However, existing modelling studies largely focus on bank erosion and overlook bank collapse. We build a bank retreat model coupling hydrodynamics, bank erosion and bank collapse. To simulate the process of bank collapse, a stress-deformation model is utilized to calculate the stress variation of bank soil after bank erosion, and the Mohr-Coulomb failure criterion is then applied to evaluate the stability of the tidal creek bank. Results show that the bank failure process can be categorized into three stages, i.e., shear failure at the bank toe (stage I), tensile failure on the bank top (stage II), and sectional cracking from the bank top to the toe (stage III). With only bank erosion, the planimetric shapes of tidal creeks are funneled due to the gradually seaward increasing discharge. In contrast to bank erosion, bank collapse is discontinuous, and the contribution of bank collapse to bank retreat can reach 85%, highlighting that the expansion of tidal creeks can be dominated by bank collapse process. The planimetric shapes of tidal creeks are funneled with a much faster expansion rate when bank collapse is considered. Overall, this study makes a further step toward more physical and realistic simulation of bank retreat in estuarine and coastal settings and the developed bank collapse module can be readily included in other morphodynamic models.

Long-Term Evaluation of Ocean Tidal Variation Models of Polar Motion and UT1

Science.gov (United States)

Karbon, Maria; Balidakis, Kyriakos; Belda, Santiago; Nilsson, Tobias; Hagedoorn, Jan; Schuh, Harald

2018-04-01

Recent improvements in the development of VLBI (very long baseline interferometry) and other space geodetic techniques such as the global navigation satellite systems (GNSS) require very precise a-priori information of short-period (daily and sub-daily) Earth rotation variations. One significant contribution to Earth rotation is caused by the diurnal and semi-diurnal ocean tides. Within this work, we developed a new model for the short-period ocean tidal variations in Earth rotation, where the ocean tidal angular momentum model and the Earth rotation variation have been setup jointly. Besides the model of the short-period variation of the Earth's rotation parameters (ERP), based on the empirical ocean tide model EOT11a, we developed also ERP models, that are based on the hydrodynamic ocean tide models FES2012 and HAMTIDE. Furthermore, we have assessed the effect of uncertainties in the elastic Earth model on the resulting ERP models. Our proposed alternative ERP model to the IERS 2010 conventional model considers the elastic model PREM and 260 partial tides. The choice of the ocean tide model and the determination of the tidal velocities have been identified as the main uncertainties. However, in the VLBI analysis all models perform on the same level of accuracy. From these findings, we conclude that the models presented here, which are based on a re-examined theoretical description and long-term satellite altimetry observation only, are an alternative for the IERS conventional model but do not improve the geodetic results.

The tidal hydrodynamics modeling of the Topolobampo coastal lagoon system and the implications for pollutant dispersion

International Nuclear Information System (INIS)

Montano-Ley, Y.; Peraza-Vizcarra, R.; Paez-Osuna, F.

2007-01-01

The tidal hydrodynamics of the Topolobampo coastal lagoon system (Mexico) has been investigated through a modified two dimensional non-linear hydrodynamic finite difference model. The advective and diffusive process acting over a hypothetical pollutant released into the coastal lagoon have also been simulated. Maxima tidal currents (0.85 m/s) were predicted within the main channel, in agree with direct measurements. The direction of the observed fastest currents (SW), also agree quite well with the direction of the strongest tidal current predicted in this investigation, which occur during the ebb when the water of the coastal lagoon is discharged into the Gulf of California. Residual currents (0.01-0.05 m/s) were also predicted. The hypothetical pollutant released within the Topolobampo Harbor would spread to both Ohuira and Topolobampo sections, reaching the inlet after approximately 12 days. - A model has been developed to simulate the tidal hydrodynamics and the behavior of a pollutant in the Topolobampo lagoon

Tidal Modulation of Ice-shelf Flow: a Viscous Model of the Ross Ice Shelf

Science.gov (United States)

Brunt, Kelly M.; MacAyeal, Douglas R.

2014-01-01

Three stations near the calving front of the Ross Ice Shelf, Antarctica, recorded GPS data through a full spring-neap tidal cycle in November 2005. The data revealed a diurnal horizontal motion that varied both along and transverse to the long-term average velocity direction, similar to tidal signals observed in other ice shelves and ice streams. Based on its periodicity, it was hypothesized that the signal represents a flow response of the Ross Ice Shelf to the diurnal tides of the Ross Sea. To assess the influence of the tide on the ice-shelf motion, two hypotheses were developed. The first addressed the direct response of the ice shelf to tidal forcing, such as forces due to sea-surface slopes or forces due to sub-ice-shelf currents. The second involved the indirect response of ice-shelf flow to the tidal signals observed in the ice streams that source the ice shelf. A finite-element model, based on viscous creep flow, was developed to test these hypotheses, but succeeded only in falsifying both hypotheses, i.e. showing that direct tidal effects produce too small a response, and indirect tidal effects produce a response that is not smooth in time. This nullification suggests that a combination of viscous and elastic deformation is required to explain the observations.

Very low tidal volume ventilation with associated hypercapnia--effects on lung injury in a model for acute respiratory distress syndrome.

Directory of Open Access Journals (Sweden)

Hans Fuchs

Full Text Available BACKGROUND: Ventilation using low tidal volumes with permission of hypercapnia is recommended to protect the lung in acute respiratory distress syndrome. However, the most lung protective tidal volume in association with hypercapnia is unknown. The aim of this study was to assess the effects of different tidal volumes with associated hypercapnia on lung injury and gas exchange in a model for acute respiratory distress syndrome. METHODOLOGY/PRINCIPAL FINDINGS: In this randomized controlled experiment sixty-four surfactant-depleted rabbits were exposed to 6 hours of mechanical ventilation with the following targets: Group 1: tidal volume = 8-10 ml/kg/PaCO(2 = 40 mm Hg; Group 2: tidal volume = 4-5 ml/kg/PaCO(2 = 80 mm Hg; Group 3: tidal volume = 3-4 ml/kg/PaCO(2 = 120 mm Hg; Group 4: tidal volume = 2-3 ml/kg/PaCO(2 = 160 mm Hg. Decreased wet-dry weight ratios of the lungs, lower histological lung injury scores and higher PaO(2 were found in all low tidal volume/hypercapnia groups (group 2, 3, 4 as compared to the group with conventional tidal volume/normocapnia (group 1. The reduction of the tidal volume below 4-5 ml/kg did not enhance lung protection. However, oxygenation and lung protection were maintained at extremely low tidal volumes in association with very severe hypercapnia and no adverse hemodynamic effects were observed with this strategy. CONCLUSION: Ventilation with low tidal volumes and associated hypercapnia was lung protective. A tidal volume below 4-5 ml/kg/PaCO(2 80 mm Hg with concomitant more severe hypercapnic acidosis did not increase lung protection in this surfactant deficiency model. However, even at extremely low tidal volumes in association with severe hypercapnia lung protection and oxygenation were maintained.

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.

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.

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

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.

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)

Observed tidal braking in the earth/moon/sun system

Science.gov (United States)

Christodoulidis, D. C.; Smith, D. E.; Williamson, R. G.; Klosko, S. M.

1987-01-01

The low degree and order terms in the spherical harmonic model of the tidal potential were observed through the perturbations which are induced on near-earth satellite orbital motions. Evaluations of tracking observations from 17 satellites and a GEM-T1 geopotential model were used in the tidal recovery which was made in the presence of over 600 long-wavelength coefficients from 32 major and minor tides. Wahr's earth tidal model was used as a basis for the recovery of the ocean tidal terms. Using this tidal model, the secular change in the moon's mean motion due to tidal dissipation was found to be -25.27 + or - 0.61 arcsec/century squared. The estimation of lunar acceleration agreed with that observed from lunar laser ranging techniques (-24.9 + or - 1.0 arcsec/century squared), with the corresponding tidal braking of earth's rotation being -5.98 + or - 0.22 x 10 to the minus 22 rad/second squared. If the nontidal braking of the earth due to the observed secular change in the earth's second zonal harmonic is considered, satellite techniques yield a total value of the secular change of the earth's rotation rate of -4.69 + or - 0.36 x 10 to the minus 22 rad/second squared.

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.

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

Digital Repository Service at National Institute of Oceanography (India)

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

A barotropic model is developed for the shelf region off the central west coast of India, which includes the regions of Bombay High and Gulf of Khambhat, in order to simulate tides and tidal currents in the region. The model is forced by a composite...

A remote sensing-based model of tidal marsh aboveground carbon stocks for the conterminous United States

Science.gov (United States)

Byrd, Kristin B.; Ballanti, Laurel; Thomas, Nathan; Nguyen, Dung; Holmquist, James R.; Simard, Marc; Windham-Myers, Lisamarie

2018-05-01

Remote sensing based maps of tidal marshes, both of their extents and carbon stocks, have the potential to play a key role in conducting greenhouse gas inventories and implementing climate mitigation policies. Our objective was to generate a single remote sensing model of tidal marsh aboveground biomass and carbon that represents nationally diverse tidal marshes within the conterminous United States (CONUS). We developed the first calibration-grade, national-scale dataset of aboveground tidal marsh biomass, species composition, and aboveground plant carbon content (%C) from six CONUS regions: Cape Cod, MA, Chesapeake Bay, MD, Everglades, FL, Mississippi Delta, LA, San Francisco Bay, CA, and Puget Sound, WA. Using the random forest machine learning algorithm, we tested whether imagery from multiple sensors, Sentinel-1 C-band synthetic aperture radar, Landsat, and the National Agriculture Imagery Program (NAIP), can improve model performance. The final model, driven by six Landsat vegetation indices and with the soil adjusted vegetation index as the most important (n = 409, RMSE = 310 g/m2, 10.3% normalized RMSE), successfully predicted biomass for a range of marsh plant functional types defined by height, leaf angle and growth form. Model results were improved by scaling field-measured biomass calibration data by NAIP-derived 30 m fraction green vegetation. With a mean plant carbon content of 44.1% (n = 1384, 95% C.I. = 43.99%-44.37%), we generated regional 30 m aboveground carbon density maps for estuarine and palustrine emergent tidal marshes as indicated by a modified NOAA Coastal Change Analysis Program map. We applied a multivariate delta method to calculate uncertainties in regional carbon densities and stocks that considered standard error in map area, mean biomass and mean %C. Louisiana palustrine emergent marshes had the highest C density (2.67 ± 0.004 Mg/ha) of all regions, while San Francisco Bay brackish/saline marshes had the highest C density of all

Inferring tidal wetland stability from channel sediment fluxes: Observations and a conceptual model

Science.gov (United States)

Ganju, Neil K.; Nidzieko, Nicholas J.; Kirwan, Matthew L.

2013-12-01

and climatic forces have modified the geomorphology of tidal wetlands over a range of timescales. Changes in land use, sediment supply, river flow, storminess, and sea level alter the layout of tidal channels, intertidal flats, and marsh plains; these elements define wetland complexes. Diagnostically, measurements of net sediment fluxes through tidal channels are high-temporal resolution, spatially integrated quantities that indicate (1) whether a complex is stable over seasonal timescales and (2) what mechanisms are leading to that state. We estimated sediment fluxes through tidal channels draining wetland complexes on the Blackwater and Transquaking Rivers, Maryland, USA. While the Blackwater complex has experienced decades of degradation and been largely converted to open water, the Transquaking complex has persisted as an expansive, vegetated marsh. The measured net export at the Blackwater complex (1.0 kg/s or 0.56 kg/m2/yr over the landward marsh area) was caused by northwesterly winds, which exported water and sediment on the subtidal timescale; tidally forced net fluxes were weak and precluded landward transport of suspended sediment from potential seaward sources. Though wind forcing also exported sediment at the Transquaking complex, strong tidal forcing and proximity to a turbidity maximum led to an import of sediment (0.031 kg/s or 0.70 kg/m2/yr). This resulted in a spatially averaged accretion of 3.9 mm/yr, equaling the regional relative sea level rise. Our results suggest that in areas where seaward sediment supply is dominant, seaward wetlands may be more capable of withstanding sea level rise over the short term than landward wetlands. We propose a conceptual model to determine a complex's tendency toward stability or instability based on sediment source, wetland channel location, and transport mechanisms. Wetlands with a reliable portfolio of sources and transport mechanisms appear better suited to offset natural and anthropogenic loss.

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....... 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...

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.

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�

Models of care choices in today's nursing workplace: where does team nursing sit?

Science.gov (United States)

Fairbrother, Greg; Chiarella, Mary; Braithwaite, Jeffrey

2015-11-01

This paper provides an overview of the developmental history of models of care (MOC) in nursing since Florence Nightingale introduced nurse training programs in a drive to make nursing a discipline-based career option. The four principal choices of models of nursing care delivery (primary nursing, individual patient allocation, team nursing and functional nursing) are outlined and discussed, and recent MOC literature reviewed. The paper suggests that, given the ways work is being rapidly reconfigured in healthcare services and the pressures on the nursing workforce projected into the future, team nursing seems to offer the best solutions.

Sediment transport and deposition on a river-dominated tidal flat: An idealized model study

Science.gov (United States)

Sherwood, Christopher R.; Chen, Shih-Nan; Geyer, W. Rockwell; Ralston, David K.

2010-01-01

A 3-D hydrodynamic model is used to investigate how different size classes of river-derived sediment are transported, exported and trapped on an idealized, river-dominated tidal flat. The model is composed of a river channel flanked by sloping tidal flats, a configuration motivated by the intertidal region of the Skagit River mouth in Washington State, United States. It is forced by mixed tides and a pulse of freshwater and sediment with various settling velocities. In this system, the river not only influences stratification but also contributes a significant cross-shore transport. As a result, the bottom stress is strongly ebb-dominated in the channel because of the seaward advance of strong river flow as the tidal flats drain during ebbs. Sediment deposition patterns and mass budgets are sensitive to settling velocity. The lateral sediment spreading scales with an advective distance (settling time multiplied by lateral flow speed), thereby confining the fast settling sediment classes in the channel. Residual sediment transport is landward on the flats, because of settling lag, but is strongly seaward in the channel. The seaward transport mainly occurs during big ebbs and is controlled by a length scale ratio Ld/XWL, where Ld is a cross-shore advective distance (settling time multiplied by river outlet velocity), and XWL is the immersed cross-shore length of the intertidal zone. Sediment trapping requires Ld/XWL stratification and reducing tidal range both favor sediment trapping, whereas varying channel geometries and asymmetry of tides has relatively small impacts. Implications of the modeling results on the south Skagit intertidal region are discussed.

A model of tidal flushing of an estuary by dipole formation

NARCIS (Netherlands)

Wells, M.G.; Heijst, van G.J.F.

2003-01-01

We discuss a laboratory model of the flushing and mixing between a bay and a sea connected by a narrow channel. Tidal changes in water elevation lead to periodic flow in and out of the bay through the narrow channel. Due to flow separation there is an asymmetry between the flow entering and leaving

Contaminant transport modelling in tidal influenced water body for low level liquid waste discharge out

International Nuclear Information System (INIS)

Singh, Sanjay; Naidu, Velamala Simhadri

2018-01-01

Low level liquid waste is generated from nuclear reactor operation and reprocessing of spent fuel. This waste is discharged into the water body after removing bulk of its radioactivity. Dispersion of contaminant mainly depends on location of outfall and hydrodynamics of water body. For radiological impact assessment, in most of the analytical formulations, source term is taken as continuous release. However, this may not be always true as the water level is influenced by tidal movement and the selected outfall may come under intertidal zone in due course of the tidal cycle. To understand these phenomena, a case study has been carried out to evaluate hydrodynamic characteristics and dilution potential of outfall located in inter-tidal zone using numerical modelling

A forward-looking, national-scale remote sensing-based model of tidal marsh aboveground carbon stocks

Science.gov (United States)

Holmquist, J. R.; Byrd, K. B.; Ballanti, L.; Nguyen, D.; Simard, M.; Windham-Myers, L.; Thomas, N.

2017-12-01

Remote sensing based maps of tidal marshes, both of their extents and carbon stocks, have the potential to play a key role in conducting greenhouse gas inventories and implementing climate mitigation policies. Our goal was to generate a single remote sensing model of tidal marsh aboveground biomass and carbon that represents nationally diverse tidal marshes within the conterminous United States (CONUS). To meet this objective we developed the first national-scale dataset of aboveground tidal marsh biomass, species composition, and aboveground plant carbon content (%C) from six CONUS regions: Cape Cod, MA, Chesapeake Bay, MD, Everglades, FL, Mississippi Delta, LA, San Francisco Bay, CA, and Puget Sound, WA. Using the random forest algorithm we tested Sentinel-1 radar backscatter metrics and Landsat vegetation indices as predictors of biomass. The final model, driven by six Landsat vegetation indices and with the soil adjusted vegetation index as the most important (n=409, RMSE=310 g/m2, 10.3% normalized RMSE), successfully predicted biomass and carbon for a range of marsh plant functional types defined by height, leaf angle and growth form. Model error was reduced by scaling field measured biomass by Landsat fraction green vegetation derived from object-based classification of National Agriculture Imagery Program imagery. We generated 30m resolution biomass maps for estuarine and palustrine emergent tidal marshes as indicated by a modified NOAA Coastal Change Analysis Program map for each region. With a mean plant %C of 44.1% (n=1384, 95% C.I.=43.99% - 44.37%) we estimated mean aboveground carbon densities (Mg/ha) and total carbon stocks for each wetland type for each region. Louisiana palustrine emergent marshes had the highest C density (2.67 ±0.08 Mg/ha) of all regions, while San Francisco Bay brackish/saline marshes had the highest C density of all estuarine emergent marshes (2.03 ±0.06 Mg/ha). This modeling and data synthesis effort will allow for aboveground

A remote sensing-based model of tidal marsh aboveground carbon stocks for the conterminous United States

Science.gov (United States)

Byrd, Kristin B.; Ballanti, Laurel; Thomas, Nathan; Nguyen, Dung; Holmquist, James R.; Simard, Marc; Windham-Myers, Lisamarie

2018-01-01

Remote sensing based maps of tidal marshes, both of their extents and carbon stocks, have the potential to play a key role in conducting greenhouse gas inventories and implementing climate mitigation policies. Our objective was to generate a single remote sensing model of tidal marsh aboveground biomass and carbon that represents nationally diverse tidal marshes within the conterminous United States (CONUS). We developed the first calibration-grade, national-scale dataset of aboveground tidal marsh biomass, species composition, and aboveground plant carbon content (%C) from six CONUS regions: Cape Cod, MA, Chesapeake Bay, MD, Everglades, FL, Mississippi Delta, LA, San Francisco Bay, CA, and Puget Sound, WA. Using the random forest machine learning algorithm, we tested whether imagery from multiple sensors, Sentinel-1 C-band synthetic aperture radar, Landsat, and the National Agriculture Imagery Program (NAIP), can improve model performance. The final model, driven by six Landsat vegetation indices and with the soil adjusted vegetation index as the most important (n = 409, RMSE = 310 g/m2, 10.3% normalized RMSE), successfully predicted biomass for a range of marsh plant functional types defined by height, leaf angle and growth form. Model results were improved by scaling field-measured biomass calibration data by NAIP-derived 30 m fraction green vegetation. With a mean plant carbon content of 44.1% (n = 1384, 95% C.I. = 43.99%–44.37%), we generated regional 30 m aboveground carbon density maps for estuarine and palustrine emergent tidal marshes as indicated by a modified NOAA Coastal Change Analysis Program map. We applied a multivariate delta method to calculate uncertainties in regional carbon densities and stocks that considered standard error in map area, mean biomass and mean %C. Louisiana palustrine emergent marshes had the highest C density (2.67 ± 0.004 Mg/ha) of all regions, while San Francisco Bay brackish/saline marshes had

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.

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.

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.

High-Accuracy Tidal Flat Digital Elevation Model Construction Using TanDEM-X Science Phase Data

Science.gov (United States)

Lee, Seung-Kuk; Ryu, Joo-Hyung

2017-01-01

This study explored the feasibility of using TanDEM-X (TDX) interferometric observations of tidal flats for digital elevation model (DEM) construction. Our goal was to generate high-precision DEMs in tidal flat areas, because accurate intertidal zone data are essential for monitoring coastal environment sand erosion processes. To monitor dynamic coastal changes caused by waves, currents, and tides, very accurate DEMs with high spatial resolution are required. The bi- and monostatic modes of the TDX interferometer employed during the TDX science phase provided a great opportunity for highly accurate intertidal DEM construction using radar interferometry with no time lag (bistatic mode) or an approximately 10-s temporal baseline (monostatic mode) between the master and slave synthetic aperture radar image acquisitions. In this study, DEM construction in tidal flat areas was first optimized based on the TDX system parameters used in various TDX modes. We successfully generated intertidal zone DEMs with 57-m spatial resolutions and interferometric height accuracies better than 0.15 m for three representative tidal flats on the west coast of the Korean Peninsula. Finally, we validated these TDX DEMs against real-time kinematic-GPS measurements acquired in two tidal flat areas; the correlation coefficient was 0.97 with a root mean square error of 0.20 m.

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

Organising nursing practice into care models that catalyse quality: A clinical nurse leader case study.

Science.gov (United States)

Bender, Miriam; Spiva, LeeAnna; Su, Wei; Hites, Lisle

2018-02-09

To determine the power of a conceptual clinical nurse leader practice model to explain the care model's enactment and trajectory in real world settings. How nursing, organised into specific models of care, functions as an organisational strategy for quality is not well specified. Clinical nurse leader integrated care delivery is one emerging model with growing adoption. A recently validated clinical nurse leader practice model conceptualizes the care model's characteristics and hypothesizes their mechanisms of action. Pattern matching case study design and mixed methods were used to determine how the care model's constructs were operationalized in one regional United States health system that integrated clinical nurse leaders into their care delivery system in 2010. The findings confirmed the empirical presence of all clinical nurse leader practice model constructs and provided a rich description of how the health system operationalized the constructs in practice. The findings support the hypothesized model pathway from Clinical Nurse Leader structuring to Clinical Nurse Leader practice and outcomes. The findings indicate analytic generalizability of the clinical nurse leader practice model. Nursing practice organised to focus on microsystem care processes can catalyse multidisciplinary engagement with, and consistent enactment of, quality practices. The model has great potential for transferability across diverse health systems. © 2018 John Wiley & Sons Ltd.

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.

Bridging Scales: A Model-Based Assessment of the Technical Tidal-Stream Energy Resource off Massachusetts, USA

Science.gov (United States)

Cowles, G. W.; Hakim, A.; Churchill, J. H.

2016-02-01

Tidal in-stream energy conversion (TISEC) facilities provide a highly predictable and dependable source of energy. Given the economic and social incentives to migrate towards renewable energy sources there has been tremendous interest in the technology. Key challenges to the design process stem from the wide range of problem scales extending from device to array. In the present approach we apply a multi-model approach to bridge the scales of interest and select optimal device geometries to estimate the technical resource for several realistic sites in the coastal waters of Massachusetts, USA. The approach links two computational models. To establish flow conditions at site scales ( 10m), a barotropic setup of the unstructured grid ocean model FVCOM is employed. The model is validated using shipboard and fixed ADCP as well as pressure data. For device scale, the structured multiblock flow solver SUmb is selected. A large ensemble of simulations of 2D cross-flow tidal turbines is used to construct a surrogate design model. The surrogate model is then queried using velocity profiles extracted from the tidal model to determine the optimal geometry for the conditions at each site. After device selection, the annual technical yield of the array is evaluated with FVCOM using a linear momentum actuator disk approach to model the turbines. Results for several key Massachusetts sites including comparison with theoretical approaches will be presented.

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.

A numerical study of local variations in tidal regime of Tagus estuary, Portugal.

Science.gov (United States)

Dias, João Miguel; Valentim, Juliana Marques; Sousa, Magda Catarina

2013-01-01

Tidal dynamics of shallow estuaries and lagoons is a complex matter that has attracted the attention of a large number of researchers over the last few decades. The main purpose of the present work is to study the intricate tidal dynamics of the Tagus estuary, which states as the largest estuary of the Iberian Peninsula and one of the most important wetlands in Portugal and Europe. Tagus has large areas of low depth and a remarkable geomorphology, both determining the complex propagation of tidal waves along the estuary of unknown manner. A non-linear two-dimensional vertically integrated hydrodynamic model was considered to be adequate to simulate its hydrodynamics and an application developed from the SIMSYS2D model was applied to study the tidal propagation along the estuary. The implementation and calibration of this model revealed its accuracy to predict tidal properties along the entire system. Several model runs enabled the analysis of the local variations in tidal dynamics, through the interpretation of amplitude and phase patterns of the main tidal constituents, tidal asymmetry, tidal ellipses, form factor and tidal dissipation. Results show that Tagus estuary tidal dynamics is extremely dependent on an estuarine resonance mode for the semi-diurnal constituents that induce important tidal characteristics. Besides, the estuarine coastline features and topography determines the changes in tidal propagation along the estuary, which therefore result essentially from a balance between convergence/divergence and friction and advection effects, besides the resonance effects.

Inferring tidal wetland stability from channel sediment fluxes: observations and a conceptual model

Science.gov (United States)

Ganju, Neil K.; Nidzieko, Nicholas J.; Kirwan, Matthew L.

2013-01-01

Anthropogenic and climatic forces have modified the geomorphology of tidal wetlands over a range of timescales. Changes in land use, sediment supply, river flow, storminess, and sea level alter the layout of tidal channels, intertidal flats, and marsh plains; these elements define wetland complexes. Diagnostically, measurements of net sediment fluxes through tidal channels are high-temporal resolution, spatially integrated quantities that indicate (1) whether a complex is stable over seasonal timescales and (2) what mechanisms are leading to that state. We estimated sediment fluxes through tidal channels draining wetland complexes on the Blackwater and Transquaking Rivers, Maryland, USA. While the Blackwater complex has experienced decades of degradation and been largely converted to open water, the Transquaking complex has persisted as an expansive, vegetated marsh. The measured net export at the Blackwater complex (1.0 kg/s or 0.56 kg/m2/yr over the landward marsh area) was caused by northwesterly winds, which exported water and sediment on the subtidal timescale; tidally forced net fluxes were weak and precluded landward transport of suspended sediment from potential seaward sources. Though wind forcing also exported sediment at the Transquaking complex, strong tidal forcing and proximity to a turbidity maximum led to an import of sediment (0.031 kg/s or 0.70 kg/m2/yr). This resulted in a spatially averaged accretion of 3.9 mm/yr, equaling the regional relative sea level rise. Our results suggest that in areas where seaward sediment supply is dominant, seaward wetlands may be more capable of withstanding sea level rise over the short term than landward wetlands. We propose a conceptual model to determine a complex's tendency toward stability or instability based on sediment source, wetland channel location, and transport mechanisms. Wetlands with a reliable portfolio of sources and transport mechanisms appear better suited to offset natural and

End-Tidal CO2-Guided Chest Compression Delivery Improves Survival in a Neonatal Asphyxial Cardiac Arrest Model.

Science.gov (United States)

Hamrick, Justin T; Hamrick, Jennifer L; Bhalala, Utpal; Armstrong, Jillian S; Lee, Jeong-Hoo; Kulikowicz, Ewa; Lee, Jennifer K; Kudchadkar, Sapna R; Koehler, Raymond C; Hunt, Elizabeth A; Shaffner, Donald H

2017-11-01

To determine whether end-tidal CO2-guided chest compression delivery improves survival over standard cardiopulmonary resuscitation after prolonged asphyxial arrest. Preclinical randomized controlled study. University animal research laboratory. 1-2-week-old swine. After undergoing a 20-minute asphyxial arrest, animals received either standard or end-tidal CO2-guided cardiopulmonary resuscitation. In the standard group, chest compression delivery was optimized by video and verbal feedback to maintain the rate, depth, and release within published guidelines. In the end-tidal CO2-guided group, chest compression rate and depth were adjusted to obtain a maximal end-tidal CO2 level without other feedback. Cardiopulmonary resuscitation included 10 minutes of basic life support followed by advanced life support for 10 minutes or until return of spontaneous circulation. Mean end-tidal CO2 at 10 minutes of cardiopulmonary resuscitation was 34 ± 8 torr in the end-tidal CO2 group (n = 14) and 19 ± 9 torr in the standard group (n = 14; p = 0.0001). The return of spontaneous circulation rate was 7 of 14 (50%) in the end-tidal CO2 group and 2 of 14 (14%) in the standard group (p = 0.04). The chest compression rate averaged 143 ± 10/min in the end-tidal CO2 group and 102 ± 2/min in the standard group (p tidal CO2-guided chest compression delivery. The response of the relaxation arterial pressure and cerebral perfusion pressure to the initial epinephrine administration was greater in the end-tidal CO2 group than in the standard group (p = 0.01 and p = 0.03, respectively). The prevalence of resuscitation-related injuries was similar between groups. End-tidal CO2-guided chest compression delivery is an effective resuscitation method that improves early survival after prolonged asphyxial arrest in this neonatal piglet model. Optimizing end-tidal CO2 levels during cardiopulmonary resuscitation required that chest compression delivery rate exceed current guidelines

Three-dimensional semi-idealized model for estuarine turbidity maxima in tidally dominated estuaries

NARCIS (Netherlands)

Kumar, Mohit; Schuttelaars, Henk M.; Roos, Pieter C.

2017-01-01

We develop a three-dimensional idealized model that is specifically aimed at gaining insight in the physical mechanisms resulting in the formation of estuarine turbidity maxima in tidally dominated estuaries. First, the three-dimensional equations for water motion and suspended sediment

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.

Home healthcare nurse retention and patient outcome model: discussion and model development.

Science.gov (United States)

Ellenbecker, Carol Hall; Cushman, Margaret

2012-08-01

This paper discusses additions to an empirically tested model of home healthcare nurse retention. An argument is made that the variables of shared decision-making and organizational commitment be added to the model based on the authors' previous research and additional evidence from the literature. Previous research testing the home healthcare nurse retention model established empirical relationships between nurse, agency, and area characteristics to nurse job satisfaction, intent to stay, and retention. Unexplained model variance prompted a new literature search to augment understanding of nurse retention and patient and agency outcomes. Data come from the authors' previous research, and a literature search from 1990 to 2011 on the topics organizational commitment, shared decision-making, nurse retention, patient outcomes and agency performance. The literature provides a rationale for the additional variables of shared decision-making and affective and continuous organizational commitment, linking these variables to nurse job satisfaction, nurse intent to stay, nurse retention and patient outcomes and agency performance. Implications for nursing.  The new variables in the model suggest that all agencies, even those not struggling to retain nurses, should develop interventions to enhance nurse job satisfaction to assure quality patient outcomes. The new nurse retention and patient outcome model increases our understanding of nurse retention. An understanding of the relationship among these variables will guide future research and the development of interventions to create and maintain nursing work environments that contribute to nurse affective agency commitment, nurse retention and quality of patient outcomes. © 2011 Blackwell Publishing Ltd.

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

Vertical Distribution of Tidal Flow Reynolds Stress in Shallow Sea

Institute of Scientific and Technical Information of China (English)

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

2009-01-01

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

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...

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.

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 ...

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

The development of the Professional Values Model in Nursing.

Science.gov (United States)

Kaya, Ayla; Boz, İlkay

2017-01-01

One of the most important criteria for professionalism is accumulation of knowledge that is usable in professional practice. Nursing models and theories are important elements of accumulating nursing knowledge and have a chance to guarantee the ethical professional practice. In recent years, there has been an increase in the use of models in nursing research and newly created terminology has started to be used in nursing. In this study, a new model, termed as the Professional Values Model, developed by the authors was described. Concepts comprising the conceptual framework of the model and relations between the concepts were explained. It is assumed that awareness about concepts of the model will increase not only the patients' satisfaction with nursing care, but also the nurses' job satisfaction and quality of nursing care. Contemporary literature has been reviewed and synthesized to develop this theoretical paper on the Professional Values Model in nursing. Having high values in nursing increases job satisfaction, which results in the improvement of patient care and satisfaction. Also, individual characteristics are effective in the determination of individual needs, priorities, and values. This relation, proved through research about the Professional Values Model, has been explained. With development of these concepts, individuals' satisfaction with care and nurses' job satisfaction will be enhanced, which will increase the quality of nursing care. Most importantly, nurses can take proper decisions about ethical dilemmas and take ethical action when they take these values into consideration when giving care. The Professional Values Model seems suitable for nurse managers and it is expected that testing will improve it. Implementation of the Professional Values Model by nurse managers may increase motivation of nurses they work with. It is suggested that guidance by the Professional Values Model may help in enhancement of motivation efforts of the nurse managers

Models of care in nursing: a systematic review.

Science.gov (United States)

Fernandez, Ritin; Johnson, Maree; Tran, Duong Thuy; Miranda, Charmaine

2012-12-01

This review investigated the effect of the various models of nursing care delivery using the diverse levels of nurses on patient and nursing outcomes. All published studies that investigated patient and nursing outcomes were considered. Studies were included if the nursing delivery models only included nurses with varying skill levels. A literature search was performed using the following databases: Medline (1985-2011), CINAHL (1985-2011), EMBASE (1985 to current) and the Cochrane Controlled Studies Register (Issue 3, 2011 of Cochrane Library). In addition, the reference lists of relevant studies and conference proceedings were also scrutinised. Two reviewers independently assessed the eligibility of the studies for inclusion in the review, the methodological quality and extracted details of eligible studies. Data were analysed using the RevMan software (Nordic Cochrane Centre, Copenhagen, Denmark). Fourteen studies were included in this review. The results reveal that implementation of the team nursing model of care resulted in significantly decreased incidence of medication errors and adverse intravenous outcomes, as well as lower pain scores among patients; however, there was no effect of this model of care on the incidence of falls. Wards that used a hybrid model demonstrated significant improvement in quality of patient care, but no difference in incidence of pressure areas or infection rates. There were no significant differences in nursing outcomes relating to role clarity, job satisfaction and nurse absenteeism rates between any of the models of care. Based on the available evidence, a predominance of team nursing within the comparisons is suggestive of its popularity. Patient outcomes, nurse satisfaction, absenteeism and role clarity/confusion did not differ across model comparisons. Little benefit was found within primary nursing comparisons and the cost effectiveness of team nursing over other models remains debatable. Nonetheless, team nursing does

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...

New Concept for Assessment of Tidal Current Energy in Jiangsu Coast, China

Directory of Open Access Journals (Sweden)

Ji-Sheng Zhang

2013-01-01

Full Text Available Tidal current energy has attracted more and more attentions of coastal engineers in recent years, mainly due to its advantages of low environmental impact, long-term predictability, and large energy potential. In this study, a two-dimensional hydrodynamic model is applied to predict the distribution of mean density of tidal current energy and to determine a suitable site for energy exploitation in Jiangsu Coast. The simulation results including water elevation and tidal current (speed and direction were validated with measured data, showing a reasonable agreement. Then, the model was used to evaluate the distribution of mean density of tidal current energy during springtide and neap tide in Jiangsu Coast. Considering the discontinuous performance of tidal current turbine, a new concept for assessing tidal current energy is introduced with three parameters: total operating time, dispersion of operating time, and mean operating time of tidal current turbine. The operating efficiency of tidal current turbine at three locations around radial submarine sand ridges was taken as examples for comparison, determining suitable sites for development of tidal current farm.

A taxonomy of nursing care organization models in hospitals.

Science.gov (United States)

Dubois, Carl-Ardy; D'Amour, Danielle; Tchouaket, Eric; Rivard, Michèle; Clarke, Sean; Blais, Régis

2012-08-28

Over the last decades, converging forces in hospital care, including cost-containment policies, rising healthcare demands and nursing shortages, have driven the search for new operational models of nursing care delivery that maximize the use of available nursing resources while ensuring safe, high-quality care. Little is known, however, about the distinctive features of these emergent nursing care models. This article contributes to filling this gap by presenting a theoretically and empirically grounded taxonomy of nursing care organization models in the context of acute care units in Quebec and comparing their distinctive features. This study was based on a survey of 22 medical units in 11 acute care facilities in Quebec. Data collection methods included questionnaire, interviews, focus groups and administrative data census. The analytical procedures consisted of first generating unit profiles based on qualitative and quantitative data collected at the unit level, then applying hierarchical cluster analysis to the units' profile data. The study identified four models of nursing care organization: two professional models that draw mainly on registered nurses as professionals to deliver nursing services and reflect stronger support to nurses' professional practice, and two functional models that draw more significantly on licensed practical nurses (LPNs) and assistive staff (orderlies) to deliver nursing services and are characterized by registered nurses' perceptions that the practice environment is less supportive of their professional work. This study showed that medical units in acute care hospitals exhibit diverse staff mixes, patterns of skill use, work environment design, and support for innovation. The four models reflect not only distinct approaches to dealing with the numerous constraints in the nursing care environment, but also different degrees of approximations to an "ideal" nursing professional practice model described by some leaders in the

Assessment of Kinetic Tidal Energy Resources Using SELFE

OpenAIRE

Manasa Ranjan Behera; Pavel Tkalich

2014-01-01

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 fo...

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

Modelling the transport and decay processes of microbial tracers in a macro-tidal estuary.

Science.gov (United States)

Abu-Bakar, Amyrhul; Ahmadian, Reza; Falconer, Roger A

2017-10-15

The Loughor Estuary is a macro-tidal coastal basin, located along the Bristol Channel, in the South West of the U.K. The maximum spring tidal range in the estuary is up to 7.5 m, near Burry Port Harbour. This estuarine region can experience severe coastal flooding during high spring tides, including extreme flooding of the intertidal saltmarshes at Llanrhidian, as well as the lower industrial and residential areas at Llanelli and Gowerton. The water quality of this estuarine basin needs to comply with the designated standards for safe recreational bathing and shellfish harvesting industries. The waterbody however, potentially receives overloading of bacterial inputs that enter the estuarine system from both point and diffuse sources. Therefore, a microbial tracer study was carried out to get a better understanding of the faecal bacteria sources and to enable a hydro-environmental model to be refined and calibrated for both advection and dispersion transport. A two-dimensional hydro-environmental model has been refined and extended to predict the highest water level covering the intertidal floodplains of the Loughor Estuary. The validated hydrodynamic model for both water levels and currents, was included with the injected mass of microbial tracer, i.e. MS2 coliphage from upstream of the estuary, and modelled as a non-conservative tracer over several tidal cycles through the system. The calibration and validation of the transport and decay of microbial tracer was undertaken, by comparing the model results and the measured data at two different sampling locations. The refined model developed as a part of this study, was used to acquire a better understanding of the water quality processes and the potential sources of bacterial pollution in the estuary. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Understanding the Influence of Retention Basin on Tidal Dynamics in Tidal Estuaries

Science.gov (United States)

Kumar, Mohit; Schuttelaars, Henk; Roos, Pieter

2014-05-01

Both the tidal motion and suspended sediment concentration (SSC) in tidal embayments and estuaries are influenced by anthropogenic (e.g. deepening ) and natural changes. An example of such an estuary is the Ems estuary, situated on the border of the Netherlands and Germany. The mean tidal range towards the end of the Ems estuary has increased from 1.5m in the 1950s to more than 3m in the 1990s while the suspended concentration has increased by a factor 10. To possibly reduce these negative effects, the construction of retention basin(s) (RB) is considered. In this contribution, the influence of location and geometry of RBs on tidal dynamics and SSC is investigated. For this purpose, a three-dimensional semi-analytic idealized model is developed. This model is an extension of the model proposed by Winant (2007) to arbitrary domain and realistic bathymetry with partial slip boundary condition at the bottom. The sea surface elevation (SSE) is calculated numerically using a finite element method. Next, the three-dimensional velocities are calculated by combining the analytically calculated vertical profiles and the gradients of the SSE which are obtained numerically. Firstly, the influence of a RB on the tidal dynamics in an infinitely long, rectangular, frictionless estuary is considered. The SSE decreases when the RB is located between a node and a landward antinode, consistent with the work of Alebregtse et al. (2013). Secondly, an estuary of finite length is connected to a sea. By varying the width of the sea, not only the effect of the distance of the RB to the landward end plays a role, but also the distance to the open sea becomes important. Finally, we discuss the influence of a RB on the tidal motion and initial sediment transport, considering the Ems estuary with realistic bathymetry. Results show that the SSE at the landward end of the Ems estuary decreases for all locations of the RBs. This decrease is most pronounced for the RB which is closest to the end

On the Formation of Ultra-Difuse Galaxies as Tidally-Stripped Systems

Science.gov (United States)

Carleton, Timothy; Cooper, Michael; Kaplinghat, Manoj; Errani, Raphael; Penarrubia, Jorge

2018-01-01

The recent identification of a large population of so-called 'Ultra-Diffuse' Galaxies (UDGs), with stellar masses ~108 M⊙, but half light radii over 1.5 kpc, has challenged our understanding of galaxy evolution. Motivated by the environmental dependence of UDG properties and abundance, I present a model for the formation of UDGs through tidal-stripping of dwarf galaxies in cored dark matter halos. To test this scenario, I utilize results from simulations of tidal stripping, which demonstrate that changes in the stellar profile of a tidally stripped galaxy can be written as a function of the amount of tidal stripping experienced by the halo (tidal tracks). These tracks, however, are different for cored and cuspy halos. Additional simulations show how the halo responds to tidal interactions given the halo orbit within a cluster.In particular, dwarf elliptical galaxies, born in 1010-10.5 M⊙ halos, expand significantly as a result of tidal stripping and produce UDGs. Applying these models to the population of halos in the Bolshoi simulation, I am able to follow the effects of tidal stripping on the dwarf galaxy population in clusters. Using tidal tracks for cuspy halos does not reproduce the observed properties of UDGs. However, using the tidal tracks for cored halos, I reproduce the distribution of sizes, stellar masses, and abundance of UDGs in clusters remarkably well.

Advancing nursing scholarship: the Mozambique model.

Science.gov (United States)

Bruce, Judith C; Dippenaar, Joan; Schmollgruber, Shelley; Mphuthi, David D; Huiskamp, Agnes

2017-01-01

Despite the importance of Human Resources for Health for the development and functioning of health systems worldwide, many countries continue to be plagued by poor health systems and a lack of adequate health care. Health systems failures may be attributed to both quantitative and qualitative nursing shortages including the lack of advanced skills to lead health initiatives, to conduct research and to educate other nurses. The response by development partners is usually framed around the production of skilled nurses through the processes of up-skilling and scaling-up. The outcome is expanded practice but with scant attention to the professional advancement of nurses. In this paper we present a two-phased capacity development model that adopted professionalization strategies to advance nursing scholarship and consequent postgraduate specialization of the first cohort of nurses in Mozambique. The main objectives were to: develop and implement a clinical course work master's degree in nursing; and ensure sustainability by capacitating the host institution to continue with the master's programme following graduation. Rigorous processes for project discussions, negotiations and monitoring were necessary amid limited resources and a challenging political climate. Forging in-country partnerships, sustaining alliances and government investment are thus key to the success of the Mozambique model. Notwithstanding some difficulties, the process unfolded over a five-year period, graduating the first cohort of 11 senior nurses with a master's degree, specializing either in critical care and trauma nursing, or maternal and neonatal health. Bridging the skills gap between generalist and specialist nurses is essential for them to manage complex and high acuity cases and to reverse associated morbidity and mortality. We conclude that this model serves as a professionalization strategy to advance nurses' scholarship of clinical practice, research and teaching.

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.

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.

Tidal heating in multilayered terrestrial exoplanets

Energy Technology Data Exchange (ETDEWEB)

Henning, Wade G.; Hurford, Terry, E-mail: wade.g.henning@nasa.gov [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)

2014-07-01

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.

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.

Bending the law: tidal bending and its effects on ice viscosity and flow

Science.gov (United States)

Rosier, S.; Gudmundsson, G. H.

2017-12-01

Many ice shelves are subject to strong ocean tides and, in order to accommodate this vertical motion, the ice must bend within the grounding zone. This tidal bending generates large stresses within the ice, changing its effective viscosity. For a confined ice shelf, this is particularly relevant because the tidal bending stresses occur along the sidewalls, which play an important role in the overall flow regime of the ice shelf. Hence, tidal bending stresses will affect both the mean and time-varying components of ice shelf flow. GPS measurements reveal strong variations in horizontal ice shelf velocities at a variety of tidal frequencies. We show, using full-Stokes viscoelastic modelling, that inclusion of tidal bending within the model accounts for much of the observed tidal modulation of horizontal ice shelf flow. Furthermore, our model shows that in the absence of a vertical tidal forcing, the mean flow of the ice shelf is reduced considerably.

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.

Simultaneous perturbation stochastic approximation for tidal models

KAUST Repository

Altaf, M.U.; Heemink, A.W.; Verlaan, M.; Hoteit, Ibrahim

2011-01-01

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.

Can barrier islands survive sea level rise? Tidal inlets versus storm overwash

Science.gov (United States)

Nienhuis, J.; Lorenzo-Trueba, J.

2017-12-01

Barrier island response to sea level rise depends on their ability to transgress and move sediment to the back barrier, either through flood-tidal delta deposition or via storm overwash. Our understanding of these processes over decadal to centennial timescales, however, is limited and poorly constrained. We have developed a new barrier inlet environment (BRIE) model to better understand the interplay between tidal dynamics, overwash fluxes, and sea-level rise on barrier evolution. The BRIE model combines existing overwash and shoreface formulations [Lorenzo-Trueba and Ashton, 2014] with alongshore sediment transport, inlet stability [Escoffier, 1940], inlet migration and flood-tidal delta deposition [Nienhuis and Ashton, 2016]. Within BRIE, inlets can open, close, migrate, merge with other inlets, and build flood-tidal delta deposits. The model accounts for feedbacks between overwash and inlets through their mutual dependence on barrier geometry. Model results suggest that when flood-tidal delta deposition is sufficiently large, barriers require less storm overwash to transgress and aggrade during sea level rise. In particular in micro-tidal environments with asymmetric wave climates and high alongshore sediment transport, tidal inlets are effective in depositing flood-tidal deltas and constitute the majority of the transgressive sediment flux. Additionally, we show that artificial inlet stabilization (via jetty construction or maintenance dredging) can make barrier islands more vulnerable to sea level rise. Escoffier, F. F. (1940), The Stability of Tidal Inlets, Shore and Beach, 8(4), 114-115. Lorenzo-Trueba, J., and A. D. Ashton (2014), Rollover, drowning, and discontinuous retreat: Distinct modes of barrier response to sea-level rise arising from a simple morphodynamic model, J. Geophys. Res. Earth Surf., 119(4), 779-801, doi:10.1002/2013JF002941. Nienhuis, J. H., and A. D. Ashton (2016), Mechanics and rates of tidal inlet migration: Modeling and application to

An innovative modeling approach using Qual2K and HEC-RAS integration to assess the impact of tidal effect on River Water quality simulation.

Science.gov (United States)

Fan, Chihhao; Ko, Chun-Han; Wang, Wei-Shen

2009-04-01

Water quality modeling has been shown to be a useful tool in strategic water quality management. The present study combines the Qual2K model with the HEC-RAS model to assess the water quality of a tidal river in northern Taiwan. The contaminant loadings of biochemical oxygen demand (BOD), ammonia nitrogen (NH(3)-N), total phosphorus (TP), and sediment oxygen demand (SOD) are utilized in the Qual2K simulation. The HEC-RAS model is used to: (i) estimate the hydraulic constants for atmospheric re-aeration constant calculation; and (ii) calculate the water level profile variation to account for concentration changes as a result of tidal effect. The results show that HEC-RAS-assisted Qual2K simulations taking tidal effect into consideration produce water quality indices that, in general, agree with the monitoring data of the river. Comparisons of simulations with different combinations of contaminant loadings demonstrate that BOD is the most import contaminant. Streeter-Phelps simulation (in combination with HEC-RAS) is also performed for comparison, and the results show excellent agreement with the observed data. This paper is the first report of the innovative use of a combination of the HEC-RAS model and the Qual2K model (or Streeter-Phelps equation) to simulate water quality in a tidal river. The combination is shown to provide an alternative for water quality simulation of a tidal river when available dynamic-monitoring data are insufficient to assess the tidal effect of the river.

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...

Modelling lateral entrapment of suspended sediment in estuaries : The role of spatial lags in settling and M4 tidal flow

NARCIS (Netherlands)

Yang, Zhongyong; de Swart, Huib E.; Cheng, Heqin; Jiang, Chenjuan; Valle-Levinson, Arnoldo

2014-01-01

The effect of the joint action of M2 and M4 tidal flow, residual flow and spatial settling lag on the lateral entrapment of sediment is examined in tidally dominated estuaries with an idealized model that assumes along-estuary uniform conditions. Approximate solutions are obtained for arbitrary

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)

Prediction of Tidal Elevations and Barotropic Currents in the Gulf of Bone

Science.gov (United States)

Purnamasari, Rika; Ribal, Agustinus; Kusuma, Jeffry

2018-03-01

Tidal elevation and barotropic current predictions in the gulf of Bone have been carried out in this work based on a two-dimensional, depth-integrated Advanced Circulation (ADCIRC-2DDI) model for 2017. Eight tidal constituents which were obtained from FES2012 have been imposed along the open boundary conditions. However, even using these very high-resolution tidal constituents, the discrepancy between the model and the data from tide gauge is still very high. In order to overcome such issues, Green’s function approach has been applied which reduced the root-mean-square error (RMSE) significantly. Two different starting times are used for predictions, namely from 2015 and 2016. After improving the open boundary conditions, RMSE between observation and model decreased significantly. In fact, RMSEs for 2015 and 2016 decreased 75.30% and 88.65%, respectively. Furthermore, the prediction for tidal elevations as well as tidal current, which is barotropic current, is carried out. This prediction was compared with the prediction conducted by Geospatial Information Agency (GIA) of Indonesia and we found that our prediction is much better than one carried out by GIA. Finally, since there is no tidal current observation available in this area, we assume that, when tidal elevations have been fixed, then the tidal current will approach the actual current velocity.

Application of a model of social information processing to nursing theory: how nurses respond to patients.

Science.gov (United States)

Sheldon, Lisa Kennedy; Ellington, Lee

2008-11-01

This paper is a report of a study to assess the applicability of a theoretical model of social information processing in expanding a nursing theory addressing how nurses respond to patients. Nursing communication affects patient outcomes such as anxiety, adherence to treatments and satisfaction with care. Orlando's theory of nursing process describes nurses' reactions to patients' behaviour as generating a perception, thought and feeling in the nurse and then action by the nurse. A model of social information processing describes the sequential steps in the cognitive processes used to respond to social cues and may be useful in describing the nursing process. Cognitive interviews were conducted in 2006 with a convenience sample of 5 nurses in the United States of America. The data were interpreted using the Crick and Dodge model of social information processing. Themes arising from cognitive interviews validated concepts of the nursing theory and the constructs of the model of social information processing. The interviews revealed that the support of peers was an additional construct involved in the development of communication skills, creation of a database and enhancement of self-efficacy. Models of social information processing enhance understanding of the process of how nurses respond to patients and further develop nursing theories further. In combination, the theories are useful in developing research into nurse-patient communication. Future research based on the expansion of nursing theory may identify effective and culturally appropriate nurse response patterns to specific patient interactions with implications for nursing care and patient outcomes.

Role modeling excellence in clinical nursing practice.

Science.gov (United States)

Perry, R N Beth

2009-01-01

Role modeling excellence in clinical nursing practice is the focus of this paper. The phenomenological research study reported involved a group of 8 nurses identified by their colleagues as exemplary. The major theme revealed in this study was that these exemplary nurses were also excellent role models in the clinical setting. This paper details approaches used by these nurses that made them excellent role models. Specifically, the themes of attending to the little things, making connections, maintaining a light-hearted attitude, modeling, and affirming others are presented. These themes are discussed within the framework of Watson [Watson, J., 1989. Human caring and suffering: a subjective model for health services. In: Watson, J., Taylor, R. (Eds.), They Shall Not Hurt: Human Suffering and Human Caring. Colorado University, Boulder, CO] "transpersonal caring" and [Bandura, A., 1997. Social Learning Theory. Prentice Hall, Englewood Cliffs, NJ] "Social Learning Theory." Particular emphasis in the discussion is on how positive role modeling by exemplary practitioners can contribute to the education of clinical nurses in the practice setting.

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.

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.

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.

Will Tidal Wetland Restoration Enhance Populations of Native Fishes?

Directory of Open Access Journals (Sweden)

Larry R. Brown

2003-10-01

Full Text Available Restoration of tidal wetlands might enhance populations of native fishes in the San Francisco Estuary of California. The purpose of this paper is to: (1 review the currently available information regarding the importance of tidal wetlands to native fishes in the San Francisco Estuary, (2 construct conceptual models on the basis of available information, (3 identify key areas of scientific uncertainty, and (4 identify methods to improve conceptual models and reduce uncertainty. There are few quantitative data to suggest that restoration of tidal wetlands will substantially increase populations of native fishes. On a qualitative basis, there is some support for the idea that tidal wetland restoration will increase populations of some native fishes; however, the species deriving the most benefit from restoration might not be of great management concern at present. Invasion of the San Francisco Estuary by alien plants and animals appears to be a major factor in obscuring the expected link between tidal wetlands and native fishes. Large-scale adaptive management experiments (>100 hectares appear to be the best available option for determining whether tidal wetlands will provide significant benefit to native fishes. Even if these experiments are unsuccessful at increasing native fish populations, the restored wetlands should benefit native birds, plants, and other organisms.

Characterising the spatial variability of the tidal stream energy resource from floating turbines

Science.gov (United States)

Ward, Sophie; Neill, Simon; Robins, Peter

2017-04-01

The shelf seas, in particular the northwest European shelf seas surrounding the UK, contain significant tidal power potential. Tidal stream energy is both predictable and reliable providing that sites are well-selected based upon the hydrodynamic regime and the device specifics. In this high resolution three-dimensional tidal modelling study, we investigate how the tidal stream resource around the Welsh coast (UK) varies with water depth and location, with particular focus on the Pembrokeshire region. The potential extractable energy for a floating tidal stream energy converter is compared with that for a bottom-fixed device, highlighting the need to vary the resource characterisation criteria based on device specifics. We demonstrate how small variations in the tidal current speeds - with hub depth or due to tidal asymmetry - can lead to substantial variations in potential power output. Further, the results indicate that power generation from floating tidal energy converters will be more significantly influenced by tidal elevations in regions characterised by a lower tidal range (more progressive waves) than regions that experience a high tidal range (standing waves). As numerical modelling capacity improves and tidal stream energy converter technologies develop, ongoing improved quantification of the tidal resource is needed, as well as consideration of the possible feedbacks of the devices and energy extraction on the hydrodynamic regime and the surrounding area.

From bedside to classroom: the nurse educator transition model.

Science.gov (United States)

Schoening, Anne M

2013-01-01

The purpose of this qualitative study was to generate a theoretical model that describes the social process that occurs during the role transition from nurse to nurse educator. Recruitment and retention of qualified nurse educators is essential in order to remedy the current staff nurse and faculty shortage in the United States, yet nursing schools face many challenges in this area. This grounded theory study utilized purposive, theoretical sampling to identify 20 nurse educators teaching in baccalaureate nursing programs in the Midwest. The Nurse Educator Transition (NET) model was created from these data.This model identifies four phases in the role transition from nurse to nurse educator: a) the Anticipatory/Expectation Phase, b) the Disorientation Phase, c) the Information-Seeking Phase, and d) the Identity Formation Phase. Recommendations include integrating formal pedagogical education into nursing graduate programs and creating evidence-based orientation and mentoring programs for novice nurse faculty.

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.)

Seasonal behaviour of tidal inlets in a tropical monsoon area

NARCIS (Netherlands)

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

2008-01-01

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

New Careers in Nursing: An Effective Model for Increasing Nursing Workforce Diversity.

Science.gov (United States)

Craft-Blacksheare, Melva

2018-03-01

The Robert Wood Johnson Foundation and the American Association of Colleges of Nursing developed the New Careers in Nursing (NCIN) program to address the nursing shortage, increase workforce diversity, and raise the profession's educational level. The program provided scholarships to second-degree underrepresented or economically disadvantaged (UED) students attending an accelerated nursing program to earn a Bachelor of Science in Nursing degree. A midwestern university received three academic-year cycles of NCIN funding. The program's model, resources, and functioning are described. The NCIN provided exceptional financial and program support that received high marks from participants. During the three award cycles, 20 UED scholars graduated with a Bachelor of Science in Nursing degree. Nineteen of the 20 scholars passed the NCLEX-RN on the first attempt. While the NCIN program has ended, nursing school administrators and faculty wishing to promote UED student success should consider using the program's model and resources as the basis for their own program. [J Nurs Educ. 2018;57(3):178-183.]. Copyright 2018, SLACK Incorporated.

Effects of using the developing nurses' thinking model on nursing students' diagnostic accuracy.

Science.gov (United States)

Tesoro, Mary Gay

2012-08-01

This quasi-experimental study tested the effectiveness of an educational model, Developing Nurses' Thinking (DNT), on nursing students' clinical reasoning to achieve patient safety. Teaching nursing students to develop effective thinking habits that promote positive patient outcomes and patient safety is a challenging endeavor. Positive patient outcomes and safety are achieved when nurses accurately interpret data and subsequently implement appropriate plans of care. This study's pretest-posttest design determined whether use of the DNT model during 2 weeks of clinical postconferences improved nursing students' (N = 83) diagnostic accuracy. The DNT model helps students to integrate four constructs-patient safety, domain knowledge, critical thinking processes, and repeated practice-to guide their thinking when interpreting patient data and developing effective plans of care. The posttest scores of students from the intervention group showed statistically significant improvement in accuracy. Copyright 2012, SLACK Incorporated.

Tidal Simulations of an Incised-Valley Fluvial System with a Physics-Based Geologic Model

Science.gov (United States)

Ghayour, K.; Sun, T.

2012-12-01

Physics-based geologic modeling approaches use fluid flow in conjunction with sediment transport and deposition models to devise evolutionary geologic models that focus on underlying physical processes and attempt to resolve them at pertinent spatial and temporal scales. Physics-based models are particularly useful when the evolution of a depositional system is driven by the interplay of autogenic processes and their response to allogenic controls. This interplay can potentially create complex reservoir architectures with high permeability sedimentary bodies bounded by a hierarchy of shales that can effectively impede flow in the subsurface. The complex stratigraphy of tide-influenced fluvial systems is an example of such co-existing and interacting environments of deposition. The focus of this talk is a novel formulation of boundary conditions for hydrodynamics-driven models of sedimentary systems. In tidal simulations, a time-accurate boundary treatment is essential for proper imposition of tidal forcing and fluvial inlet conditions where the flow may be reversed at times within a tidal cycle. As such, the boundary treatment at the inlet has to accommodate for a smooth transition from inflow to outflow and vice-versa without creating numerical artifacts. Our numerical experimentations showed that boundary condition treatments based on a local (frozen) one-dimensional approach along the boundary normal which does not account for the variation of flow quantities in the tangential direction often lead to unsatisfactory results corrupted by numerical artifacts. In this talk, we propose a new boundary treatment that retains all spatial and temporal terms in the model and as such is capable to account for nonlinearities and sharp variations of model variables near boundaries. The proposed approach borrows heavily from the idea set forth by J. Sesterhenn1 for compressible Navier-Stokes equations. The methodology is successfully applied to a tide-influenced incised

impact of vegetation on flow routing and sedimentation patterns : three-dimensional modeling for a tidal marsh

NARCIS (Netherlands)

Temmerman, S.; Bouma, T.J.; De Vries, M.B.; Wang, Z.B.; Govers, G.; Herman, P.M.J.

2005-01-01

A three-dimensional hydrodynamic and sediment transport model was used to study the relative impact of (1) vegetation, (2) micro-topography, and (3) water level fluctuations on the spatial flow and sedimentation patterns in a tidal marsh landscape during single inundation events. The model

Impact of vegetation on flow routing and sedimentation patterns : three-dimensional modeling for a tidal marsh

NARCIS (Netherlands)

Temmerman, S.; Bouma, T.J.; Govers, G.; Wang, Z.B.; de Vries, M.B.; Herman, P.M.J.

2005-01-01

A three-dimensional hydrodynamic and sediment transport model was used to study the relative impact of (1) vegetation, (2) micro-topography, and (3) water level fluctuations on the spatial flow and sedimentation patterns in a tidal marsh landscape during single inundation events. The model

Nurse Work Engagement Impacts Job Outcome and Nurse-Assessed Quality of Care: Model Testing with Nurse Practice Environment and Nurse Work Characteristics as Predictors

Directory of Open Access Journals (Sweden)

Peter Mathieu Van Bogaert

2014-11-01

Full Text Available Key words: burnout,job satisfaction, nurse retention, nurse practice environment,quality of care, acute health care,structural equation modelling. Aim:To explore the mechanisms through which nurse practice environment dimensions are associated with job outcomes and nurse-assessed quality of care. Mediating variables tested included nurse work characteristics of workload, social capital, decision latitude, as well as work engagement dimensions of vigor, dedication and absorption.Background: Understanding to support and guide the practice community in their daily effort to answer most accurate complex care demands along with a stable nurse workforce are challenging.Design: Cross-sectional survey.Method:Based on previous empirical findings,a structural equation model designed with valid measurement instruments was tested.The study population was registered acute care hospital nurses(N = 1201 in twoindependent hospitals and one hospital group with six hospitals in Belgium.Results: Nurse practice environment dimensions predicted job outcome variables and nurse ratings of quality of care.Analyses were consistent with features of nurses’ work characteristics including perceived workload,decision latitude,and social capital,as well as three dimension of work engagement playing mediating roles between nurse practice environment and outcomes.A revised model adjusted using various fit measures explained 60 % and 47 % of job outcomes and nurse - assessed quality of care,respectively.Conclusion: Study findings show that aspects of nurse work characteristics such as workload,decision latitude and social capital along with nurse work engagement(e.g.vigor, dedication and absorption play a role between how various stakeholders such as executives,nurse managers and physicians will organize care and how nurses perceive job outcomes and quality of care.

Investigating the adequacy of the Competence-Turnover Intention Model: how does nursing competence affect nurses' turnover intention?

Science.gov (United States)

Takase, Miyuki; Teraoka, Sachiko; Kousuke, Yabase

2015-03-01

The aim of this study was to test the adequacy of the Competence-Turnover Intention Model, which was developed to identify how nursing competence could affect nurses' turnover intention (nurses' intention to voluntarily leave an organisation). Recent studies have suggested that the level of nursing competence is negatively related to nurses' intention to leave their jobs, suggesting that a lack of competence threatens both the quality and quantity of the nursing workforce. However, the mechanism of how nursing competence affects nurses' turnover intention has not been explored previously. A cross-sectional survey design was used. Surveys were distributed to 1337 Japanese registered nurses/midwives in October, 2013. The adequacy of the model was analysed using structural equation modelling. In total, 766 questionnaires were returned, with a return rate of 57%. The model fitted well with the data. The results showed that the level of nursing competence was related positively to the quantity of organisational rewards they felt they had received, and negatively related to the level of exhaustion they experienced. Moreover, the perceived organisational rewards and exhaustion were correlated with nurses' turnover intention through affective commitment. The Competence-Turnover Intention Model is useful for explaining how nursing competence impacts on their turnover intention. Clinical implications derived from the findings are that: promoting nursing competence is key to improving not only the quality of care provided by nurses, but also to retaining the nursing workforce, and the model can be used to develop strategies that would mitigate their turnover intention. © 2014 John Wiley & Sons Ltd.

A taxonomy of nursing care organization models in hospitals

Science.gov (United States)

2012-01-01

Background Over the last decades, converging forces in hospital care, including cost-containment policies, rising healthcare demands and nursing shortages, have driven the search for new operational models of nursing care delivery that maximize the use of available nursing resources while ensuring safe, high-quality care. Little is known, however, about the distinctive features of these emergent nursing care models. This article contributes to filling this gap by presenting a theoretically and empirically grounded taxonomy of nursing care organization models in the context of acute care units in Quebec and comparing their distinctive features. Methods This study was based on a survey of 22 medical units in 11 acute care facilities in Quebec. Data collection methods included questionnaire, interviews, focus groups and administrative data census. The analytical procedures consisted of first generating unit profiles based on qualitative and quantitative data collected at the unit level, then applying hierarchical cluster analysis to the units’ profile data. Results The study identified four models of nursing care organization: two professional models that draw mainly on registered nurses as professionals to deliver nursing services and reflect stronger support to nurses’ professional practice, and two functional models that draw more significantly on licensed practical nurses (LPNs) and assistive staff (orderlies) to deliver nursing services and are characterized by registered nurses’ perceptions that the practice environment is less supportive of their professional work. Conclusions This study showed that medical units in acute care hospitals exhibit diverse staff mixes, patterns of skill use, work environment design, and support for innovation. The four models reflect not only distinct approaches to dealing with the numerous constraints in the nursing care environment, but also different degrees of approximations to an “ideal” nursing professional practice

Tidal phenomena in reservoirs; Fenomeno de mare em reservatorios

Energy Technology Data Exchange (ETDEWEB)

Pinilla Cortes, John Freddy

1997-06-01

This work models the oceanic tidal effect on reservoirs by coupling geomechanic principles with equations for fluid in a deformable porous media. The coupling revealed the importance of establishing properly the system compressibility under the various possible configurations of the loading system. The basic models for infinite reservoir, constant outer-pressure reservoir and closed reservoir were considered. It was verified that it was possible to apply the superposition of effects on the solution for the basic models by carrying a simple transformation on the solution variable. The problem was treated by in the context of test analysis, concerning dimensionless form of variables and the inclusion of well effects. The solution for the infinite reservoir including tidal effects. The solution for the infinite reservoir including tidal effects was obtained in the Laplace space and was inverted numerically by using Crump's routine. The results were incorporated to conventional type curves, and were validated by comparison with real and simulated pressure test data. Finally, alternate practices were suggested to integrate the well test analysis in reservoirs affected by the tidal effect. (author)

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.

Short-term tidal asymmetry inversion in a macrotidal estuary (Beira, Mozambique)

Science.gov (United States)

Nzualo, Teodósio N. M.; Gallo, Marcos N.; Vinzon, Susana B.

2018-05-01

The distortion of the tide in estuaries, bays and coastal areas is the result of the generation of overtides due to the non-linear effects associated with friction, advection, and the finite effects of the tidal amplitude in shallow waters. The Beira estuary is classified as macrotidal, with a large ratio of S2/M2. Typical tides ranges from 6 m and 0.8 m, during springs and neaps tides, respectively. As a consequence of this large fortnightly tidal amplitude difference and the estuarine morphology, asymmetry inversions occur. Two types of tidal asymmetries were investigated in this paper, one considering tidal duration asymmetry (time difference between rising and falling tide) and the other, related to tidal velocity asymmetry (unequal magnitudes of flood and ebb peaks currents). In the Beira estuary when we examine the tidal duration asymmetry, flood dominance is observed during spring tide periods (negative time difference between rising and falling tide), while ebb dominance appears during neap tides (positive time difference between rising and falling tide). A 2DH hydrodynamic model was implemented to analyze this asymmetry inversion. The model was calibrated with water-level data measured at the Port of Beira and current data measured along the estuary. The model was run for different scenarios considering tidal constituents at the ocean boundary, river discharge and the morphology of the estuary. River discharge did not show significant effects on the tidal duration asymmetry. Through comparison of the scenarios, it was shown that the incoming ocean tide at the boundary has an ebb-dominant asymmetry, changing to flood-dominant only during spring tides due to the effect of shoaling and friction within the estuary. During neap tides, the propagation occurs mainly in the channels, and ebb dominance remains. The interplay between the estuary morphodynamics was thus identified and the relation between tidal duration asymmetry and tidal velocity asymmetry was

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

From Globular Clusters to Tidal Dwarfs: Structure Formation in Tidal Tails

Science.gov (United States)

Knierman, K.; Hunsberger, S.; Gallagher, S.; Charlton, J.; Whitmore, B.; Hibbard, J.; Kundu, A.; Zaritsky, D.

1999-12-01

Galaxy interactions trigger star formation in tidal debris. How does this star formation depend on the local and global physical conditions? Using WFPC2/HST images, we investigate the range of structure within tidal tails of four classic ``Toomre Sequence'' mergers: NGC 4038/9 (``Antennae''), NGC 7252 (``Atoms for Peace''), NGC 3921, and NGC 3256. These tails contain a variety of stellar associations with sizes from globular clusters up to dwarf Irregulars. We explore whether there is a continuum between the two extremes. Our eight fields sample seven tidal tails at a variety of stages in the evolutionary sequence. Some of these tails are rich in HI while others are HI poor. Large tidal dwarfs are embedded in three of the tails. Using V and I WFPC2 images, we measure luminosities and colors of substructures within the tidal tails. The properties of globular cluster candidates in the tails will be contrasted with those of the hundreds of young clusters in the central regions of these mergers. We address whether globular clusters form and survive in the tidal tails and whether tidal dwarfs are composed of only young stars. By comparing the properties of structures in the tails of the four mergers with different ages, we examine systematic evolution of structure along the evolutionary sequence and as a function of HI content. We acknowledge support from NASA through STScI, and from NSF for an REU supplement for Karen Knierman.

Tidal influence on subtropical estuarine methane emissions

Science.gov (United States)

Sturm, Katrin; Grinham, Alistair; Werner, Ursula; Yuan, Zhiguo

2014-05-01

The relatively unstudied subtropical estuaries, particularly in the Southern Hemisphere, represent an important gap in our understanding of global greenhouse gas (GHG) emissions. These systems are likely to form an important component of GHG budgets as they occupy a relatively large surface area, over 38 000 km2 in Australia. Here, we present studies conducted in the Brisbane River estuary, a representative system within the subtropical region of Queensland, Australia. This is a highly modified system typical of 80% of Australia's estuaries. Generally, these systems have undergone channel deepening and straightening for safer shipping access and these modifications have resulted in large increases in tidal reach. The Brisbane River estuary's natural tidal reach was 16 km and this is now 85 km and tidal currents influence double the surface area (9 km2 to 18 km2) in this system. Field studies were undertaken to improve understanding of the driving factors behind methane water-air fluxes. Water-air fluxes in estuaries are usually calculated with the gas exchange coefficient (k) for currents and wind as well as the concentration difference across the water-air interface. Tidal studies in the lower and middle reaches of the estuary were performed to monitor the influence of the tidal stage (a proxy for kcurrent) on methane fluxes. Results for both investigated reaches showed significantly higher methane fluxes during the transition time of tides, the time of greatest tidal currents, than during slack tide periods. At these tidal transition times with highest methane chamber fluxes, lowest methane surface water concentrations were monitored. Modelled fluxes using only wind speed (kwind) were at least one order of magnitude lower than observed from floating chambers, demonstrating that current speed was likely the driving factor of water-air fluxes. An additional study was then conducted sampling the lower, middle and upper reaches during a tidal transition period

An analytical solution for tidal propagation in the Yangtze Estuary, China

Directory of Open Access Journals (Sweden)

E. F. Zhang

2012-09-01

Full Text Available An analytical model for tidal dynamics has been applied to the Yangtze Estuary for the first time, to describe the tidal propagation in this large and typically branched estuary with three-order branches and four outlets to the sea. This study shows that the analytical model developed for a single-channel estuary can also accurately describe the tidal dynamics in a branched estuary, particularly in the downstream part. Within the same estuary system, the North Branch and the South Branches have a distinct tidal behaviour: the former being amplified demonstrating a marine character and the latter being damped with a riverine character. The satisfactory results for the South Channel and the South Branch using both separate and combined topographies confirm that the branched estuary system functions as an entity. To further test these results, it is suggested to collect more accurate and dense bathymetric and tidal information.

Dissipation of Tidal Energy

Science.gov (United States)

2002-01-01

The moon's gravity imparts tremendous energy to the Earth, raising tides throughout the global oceans. What happens to all this energy? This question has been pondered by scientists for over 200 years, and has consequences ranging from the history of the moon to the mixing of the oceans. Richard Ray at NASA's Goddard Space Flight Center, Greenbelt, Md. and Gary Egbert of the College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Ore. studied six years of altimeter data from the TOPEX/Poseidon satellite to address this question. According to their report in the June 15 issue of Nature, about 1 terawatt, or 25 to 30 percent of the total tidal energy dissipation, occurs in the deep ocean. The remainder occurs in shallow seas, such as on the Patagonian Shelf. 'By measuring sea level with the TOPEX/Poseidon satellite altimeter, our knowledge of the tides in the global ocean has been remarkably improved,' said Richard Ray, a geophysicist at Goddard. The accuracies are now so high that this data can be used to map empirically the tidal energy dissipation. (Red areas, above) The deep-water tidal dissipation occurs generally near rugged bottom topography (seamounts and mid-ocean ridges). 'The observed pattern of deep-ocean dissipation is consistent with topographic scattering of tidal energy into internal motions within the water column, resulting in localized turbulence and mixing', said Gary Egbert an associate professor at OSU. One important implication of this finding concerns the possible energy sources needed to maintain the ocean's large-scale 'conveyor-belt' circulation and to mix upper ocean heat into the abyssal depths. It is thought that 2 terawatts are required for this process. The winds supply about 1 terawatt, and there has been speculation that the tides, by pumping energy into vertical water motions, supply the remainder. However, all current general circulation models of the oceans ignore the tides. 'It is possible that properly

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.

Role of tidal flat in material cycling in the coastal sea

OpenAIRE

Yara, Yumiko; Yanagi, Tetsuo; Montani, Shigeru; Kuninao, Tada

2007-01-01

A simple tidal flat model with pelagic and benthic ecosystems was developed in order to analyze the nitrogen cycling in an inter-tidal flat of the Seto Inland Sea, Japan. After the verification of calculation results with the observed results in water quality and benthic biomasses, the role of this tidal flat in nitrogen cycling was evaluated from the viewpoint of water quality purification capability. When there is no suspension feeder in the tidal flat, the water quality purification capab...

Effect of subseabed salt domes on Tidal Residual currents in the Persian Gulf

Science.gov (United States)

Mashayekh Poul, Hossein; Backhaus, Jan; Dehghani, Ali; Huebner, Udo

2016-05-01

Geological studies in the Persian Gulf (PG) have revealed the existence of subseabed salt-domes. With suitable filtering of a high-resolution PG seabed topography, it is seen that the domes leave their signature in the seabed, i.e., numerous hills and valleys with amplitudes of several tens of meters and radii from a few up to tens of kilometers. It was suspected that the "shark skin" of the PG seabed may affect the tidal residual flow. The interaction of tidal dynamics and these obstacles was investigated in a nonlinear hydrodynamic numerical tidal model of the PG. The model was first used to characterize flow patterns of residual currents generated by a tidal wave passing over symmetric, elongated and tilted obstacles. Thereafter it was applied to the entire PG. The model was forced at its open boundary by the four dominant tidal constituents residing in the PG. Each tidal constituent was simulated separately. Results, i.e., tidal residual currents in the PG, as depicted by Lagrangian trajectories reveal a stationary flow that is very rich in eddies. Each eddy can be identified with a topographic obstacle. This confirms that the tidal residual flow field is strongly influenced by the nonlinear interaction of the tidal wave with the bottom relief which, in turn, is deformed by salt-domes beneath the seabed. Different areas of maximum residual current velocities are identified for major tidal constituents. The pattern of trajectories indicates the presence of two main cyclonic gyres and several adjacent gyres rotating in opposite directions and a strong coastal current in the northern PG.

An analytical solution for tidal propagation in the Yangtze Estuary, China

NARCIS (Netherlands)

Zhang, E.F.; Savenije, H.H.G.; Chen, S.L.; Mao, X.H.

2012-01-01

An analytical model for tidal dynamics has been applied to the Yangtze Estuary for the first time, to describe the tidal propagation in this large and typically branched estuary with three-order branches and four outlets to the sea. This study shows that the analytical model developed for a

School nurse summer institute: a model for professional development.

Science.gov (United States)

Neighbors, Marianne; Barta, Kathleen

2004-06-01

The components of a professional development model designed to empower school nurses to become leaders in school health services is described. The model was implemented during a 3-day professional development institute that included clinical and leadership components, especially coalition building, with two follow-up sessions in the fall and spring. Coalition building is an important tool to enhance the influence of the school nurse in improving the health of individuals, families, and communities. School nurses and nursing educators with expertise in the specialty of school nursing could replicate this model in their own regions.

Spatial Distribution of Volcanic Hotspots and Paterae on Io: Implications for Tidal Heating Models and Magmatic Pathways

Science.gov (United States)

Hamilton, C. W.; Beggan, C. D.; Lopes, R.; Williams, D. A.; Radenbaugh, J.

2011-01-01

Io, the innermost of Jupiter's Galilean satellites, is the most volcanically active body in the Solar. System. Io's global mean heat flow is approximately 2 W/square m, which is approximately 20 times larger than on Earth. High surface temperatures concentrate within "hotspots" and, to date, 172 Ionian hotspots have been identified by spacecraft and Earth-based telescopes. The Laplace resonance between Io, Europa, and Ganymede maintains these satellites in noncircular orbits and causes displacement of their tidal bulges as the overhead position of Jupiter changes for each moon. Gravitational interactions between Jupiter and Io dominate the orbital evolution of the Laplacian system and generate enormous heat within to as tidal energy is dissipated. If this energy were transferred out of Io at the same rate as it is generated, then the associated surface heat flux would be 2.24 +/- 0.45 W/square m. This estimate is in good agreement with observed global heat flow, but to better constrain tidal dissipation mechanisms and infer how thermal energy is transferred to Io's surface, it is critical to closely examine the spatial distribution of volcanic features. End-member tidal dissipation models either consider that heating occurs completely in the mantle, or completely in the asthenosphere. Mixed models typically favor one-third mantle and two-thirds asthenosphere heating. Recent models also consider the effects of mantle-asthenosphere boundary permeability and asthenospheric instabilities. Deep-mantle heating models predict maximum surface heat flux near the poles, whereas asthenosphere heating models predict maxima near the equator-particularly in the Sub-Jovian and Anti-Jovian hemispheres, with smaller maxima occurring at orbit tangent longitudes. Previous studies have examined the global distribution of Ionian hotspots and patera (i.e., irregular or complex craters with scalloped edges that are generally interpreted to be volcanic calderas), but in this study, we

Assimilating data into open ocean tidal models

Science.gov (United States)

Kivman, Gennady A.

The problem of deriving tidal fields from observations by reason of incompleteness and imperfectness of every data set practically available has an infinitely large number of allowable solutions fitting the data within measurement errors and hence can be treated as ill-posed. Therefore, interpolating the data always relies on some a priori assumptions concerning the tides, which provide a rule of sampling or, in other words, a regularization of the ill-posed problem. Data assimilation procedures used in large scale tide modeling are viewed in a common mathematical framework as such regularizations. It is shown that they all (basis functions expansion, parameter estimation, nudging, objective analysis, general inversion, and extended general inversion), including those (objective analysis and general inversion) originally formulated in stochastic terms, may be considered as utilizations of one of the three general methods suggested by the theory of ill-posed problems. The problem of grid refinement critical for inverse methods and nudging is discussed.

TIDAL HEATING IN A MAGMA OCEAN WITHIN JUPITER’S MOON Io

International Nuclear Information System (INIS)

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

2015-01-01

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

Super massive black hole in galactic nuclei with tidal disruption of stars

International Nuclear Information System (INIS)

Zhong, Shiyan; Berczik, Peter; Spurzem, Rainer

2014-01-01

Tidal disruption of stars by super massive central black holes from dense star clusters is modeled by high-accuracy direct N-body simulation. The time evolution of the stellar tidal disruption rate, the effect of tidal disruption on the stellar density profile, and, for the first time, the detailed origin of tidally disrupted stars are carefully examined and compared with classic papers in the field. Up to 128k particles are used in simulation to model the star cluster around a super massive black hole, and we use the particle number and the tidal radius of the black hole as free parameters for a scaling analysis. The transition from full to empty loss-cone is analyzed in our data, and the tidal disruption rate scales with the particle number, N, in the expected way for both cases. For the first time in numerical simulations (under certain conditions) we can support the concept of a critical radius of Frank and Rees, which claims that most stars are tidally accreted on highly eccentric orbits originating from regions far outside the tidal radius. Due to the consumption of stars moving on radial orbits, a velocity anisotropy is found inside the cluster. Finally we estimate the real galactic center based on our simulation results and the scaling analysis.

Super Massive Black Hole in Galactic Nuclei with Tidal Disruption of Stars

Science.gov (United States)

Zhong, Shiyan; Berczik, Peter; Spurzem, Rainer

2014-09-01

Tidal disruption of stars by super massive central black holes from dense star clusters is modeled by high-accuracy direct N-body simulation. The time evolution of the stellar tidal disruption rate, the effect of tidal disruption on the stellar density profile, and, for the first time, the detailed origin of tidally disrupted stars are carefully examined and compared with classic papers in the field. Up to 128k particles are used in simulation to model the star cluster around a super massive black hole, and we use the particle number and the tidal radius of the black hole as free parameters for a scaling analysis. The transition from full to empty loss-cone is analyzed in our data, and the tidal disruption rate scales with the particle number, N, in the expected way for both cases. For the first time in numerical simulations (under certain conditions) we can support the concept of a critical radius of Frank & Rees, which claims that most stars are tidally accreted on highly eccentric orbits originating from regions far outside the tidal radius. Due to the consumption of stars moving on radial orbits, a velocity anisotropy is found inside the cluster. Finally we estimate the real galactic center based on our simulation results and the scaling analysis.

A model for empowerment of nursing in Iran

Directory of Open Access Journals (Sweden)

Salsali Mahvash

2005-03-01

Full Text Available Abstract Background While the Iranian nursing profession tries to reach to its full capacity for participating in the maintenance of public health, its desire to develop is strongly influenced by cultural, economic, and religious factors. The concept of empowerment is frequently used in nursing and the health services, particularly in relation to the quality of care, since the mission of nursing is to provide safe and quality nursing care thereby enabling patients to achieve their maximum level of wellness. When considering the importance of nursing services in any health system, the 54th World Health Assembly recommended that programs be designed to strengthen and promote the nursing profession. Since empowerment is crucial to the role of nurses, a qualitative study was conducted and aimed at designing a model for empowering nurses in Iran. Methods A grounded theory approach was used for analyzing the participants' experiences, their perceptions and the strategies affecting empowerment. Data collection was done through Semi-structured interviews and participant observation. Forty-four participants were interviewed and 12 sessions of observation were carried out. Results Three main categories emerged from the data collected; these are "personal empowerment", "collective empowerment", and "the culture and structure of the organization." From the participants' perspective, empowerment is a dynamic process that results from mutual interaction between personal and collective traits of nurses as well as the culture and the structure of the organization. Impediments, such as power dynamics within the health care system hinder nurses from demonstrating that they possess the essential ingredients of empowerment. Conclusion A model was designed for empowering the nursing profession in Iran. Implementing this model will not only define nursing roles, identify territories in the national healthcare system, but it will restructure nursing systems, sub

Testing a theoretical model of clinical nurses' intent to stay.

Science.gov (United States)

Cowden, Tracy L; Cummings, Greta G

2015-01-01

Published theoretical models of nurses' intent to stay (ITS) report inconsistent outcomes, and not all hypothesized models have been adequately tested. Research has focused on cognitive rather than emotional determinants of nurses' ITS. The aim of this study was to empirically verify a complex theoretical model of nurses' ITS that includes both affective and cognitive determinants and to explore the influence of relational leadership on staff nurses' ITS. The study was a correlational, mixed-method, nonexperimental design. A subsample of the Quality Work Environment Study survey data 2009 (n = 415 nurses) was used to test our theoretical model of clinical nurses' ITS as a structural equation model. The model explained 63% of variance in ITS. Organizational commitment, empowerment, and desire to stay were the model concepts with the strongest effects on nurses' ITS. Leadership practices indirectly influenced ITS. How nurses evaluate and respond to their work environment is both an emotional and rational process. Health care organizations need to be cognizant of the influence that nurses' feelings and views of their work setting have on their intention decisions and integrate that knowledge into the development of retention strategies. Leadership practices play an important role in staff nurses' perceptions of the workplace. Identifying the mechanisms by which leadership influences staff nurses' intentions to stay presents additional focus areas for developing retention strategies.

Tidal-Fluvial and Estuarine Processes in the Lower Columbia River: II. Water Level Models, Floodplain Wetland Inundation, and System Zones

Energy Technology Data Exchange (ETDEWEB)

Jay, David A.; Borde, Amy B.; Diefenderfer, Heida L.

2016-04-26

Spatially varying water-level regimes are a factor controlling estuarine and tidal-fluvial wetland vegetation patterns. As described in Part I, water levels in the Lower Columbia River and estuary (LCRE) are influenced by tides, river flow, hydropower operations, and coastal processes. In Part II, regression models based on tidal theory are used to quantify the role of these processes in determining water levels in the mainstem river and floodplain wetlands, and to provide 21-year inundation hindcasts. Analyses are conducted at 19 LCRE mainstem channel stations and 23 tidally exposed floodplain wetland stations. Sum exceedance values (SEVs) are used to compare wetland hydrologic regimes at different locations on the river floodplain. A new predictive tool is introduced and validated, the potential SEV (pSEV), which can reduce the need for extensive new data collection in wetland restoration planning. Models of water levels and inundation frequency distinguish four zones encompassing eight reaches. The system zones are the wave- and current-dominated Entrance to river kilometer (rkm) 5; the Estuary (rkm-5 to 87), comprised of a lower reach with salinity, the energy minimum (where the turbidity maximum normally occurs), and an upper estuary reach without salinity; the Tidal River (rkm-87 to 229), with lower, middle, and upper reaches in which river flow becomes increasingly dominant over tides in determining water levels; and the steep and weakly tidal Cascade (rkm-229 to 234) immediately downstream from Bonneville Dam. The same zonation is seen in the water levels of floodplain stations, with considerable modification of tidal properties. The system zones and reaches defined here reflect geological features and their boundaries are congruent with five wetland vegetation zones

A legacy building model for holistic nursing.

Science.gov (United States)

Lange, Bernadette; Zahourek, Rothlyn P; Mariano, Carla

2014-06-01

This pilot project was an effort to record the historical roots, development, and legacy of holistic nursing through the visionary spirit of four older American Holistic Nurses Association (AHNA) members. The aim was twofold: (a) to capture the holistic nursing career experiences of elder AHNA members and (b) to begin to create a Legacy Building Model for Holistic Nursing. The narratives will help initiate an ongoing, systematic method for the collection of historical data and serve as a perpetual archive of knowledge and inspiration for present and future holistic nurses. An aesthetic inquiry approach was used to conduct in-depth interviews with four older AHNA members who have made significant contributions to holistic nursing. The narratives provide a rich description of their personal and professional evolution as holistic nurses. The narratives are presented in an aesthetic format of the art forms of snapshot, pastiche, and collage rather than traditional presentations of research findings. A synopsis of the narratives is a dialogue between the three authors and provides insight for how a Legacy Model can guide our future. Considerations for practice, education, and research are discussed based on the words of wisdom from the four older holistic nurses.

Tidal residual current and its role in the mean flow on the Changjiang Bank

Science.gov (United States)

Xuan, Jiliang; Yang, Zhaoqing; Huang, Daji; Wang, Taiping; Zhou, Feng

2016-02-01

The 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 on 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%.

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%.

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

An assessment of tidal energy potential. The Lima estuary

Energy Technology Data Exchange (ETDEWEB)

Trigo-Teixeira, A. [Department of Civil Engineering and Architecture, Instituto Superior Tecnico, Lisbon Technical University, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Rebordao, I. [WW Consulting Engineers, Laveiras, Caxias 2760-032 (Portugal)

2009-07-01

A hydrodynamic model was set up for the Lima estuary (Portugal) and a preliminary assessment of the strength of tidal currents to produce tidal energy was made. To calibrate the model results were compared with measured data, and the model tuned to reproduce water levels and currents in several locations within the estuary. The data was acquired with ADCPs, during a field campaign that was planed to cover a spring-neap tide cycle, in October 2006. The Advanced Circulation Model - ADCIRC was forced with the most important harmonic constituents present in the ocean tide signal. Upstream, in the river boundary, the discharge was taken from hydrographs. The wetting and drying tool was also applied and a detailed bathymetry was considered, since there are areas in the domain where salt marshes occur, drying out at low tide. The tidal currents potential were assessed for a scenario of tidal forcing only, without any river discharge. The lower estuary is occupied by the port infrastructure and navigation channels which conflicts with any kind of equipment installation. Values of the currents and water depths given by the model indicate that some places in the main channel of the middle estuary, might be interesting to install micro turbines in the future, depending on the evolution of the requirements of this technology.

An investigation into the description of patients' problems by nurses using two different needs-based nursing models.

Science.gov (United States)

Griffiths, P

1998-11-01

This paper describes an investigation into how nurses describe patients' problems and the possible effects of an espoused nursing model on these descriptions. A descriptive study was conducted on two medical wards in a Welsh District General Hospital. Data collected were subjected to content analysis using Gordon's Functional Health Patterns to order the data. The two wards investigated, whilst being very similar in many ways, utilized different nursing models. Findings showed that the nurses studied, when describing patients' problems, most commonly used medical diagnoses or the medical reasons for admission. Patients' problems identified predominately addressed bio-physical needs with scant attention given to psycho-social needs. Despite the use of two different nursing models the language and emphasis of problem description were very similar and there was no evidence of the application of the conceptual underpinnings of the two models. It is suggested that although the use of a ready-made nursing language may have drawbacks, the British nurse should understand and assess the value of the North American Nursing Diagnosis Association's (NANDA) nursing diagnoses. Without such involvement this system may be implemented in the United Kingdom (UK) without the input and influence of practising nurses.

The Prince Edward Island Conceptual Model for Nursing: a nursing perspective of primary health care.

Science.gov (United States)

Munro, M; Gallant, M; MacKinnon, M; Dell, G; Herbert, R; MacNutt, G; McCarthy, M J; Murnaghan, D; Robertson, K

2000-06-01

The philosophy of primary health care (PHC) recognizes that health is a product of individual, social, economic, and political factors and that people have a right and a duty, individually and collectively, to participate in the course of their own health. The majority of nursing models cast the client in a dependent role and do not conceptualize health in a social, economic, and political context. The Prince Edward Island Conceptual Model for Nursing is congruent with the international move towards PHC. It guides the nurse in practising in the social and political environment in which nursing and health care take place. This model features a nurse/client partnership, the goal being to encourage clients to act on their own behalf. The conceptualization of the environment as the collective influence of the determinants of health gives both nurse and client a prominent position in the sociopolitical arena of health and health care.

Modeling equilibrium bed profiles of short tidal embayments : On the effect of the vertical distribution of suspended sediment and the influence of the boundary conditions

NARCIS (Netherlands)

Ter Brake, M.C.; Schuttelaars, H.M.

2009-01-01

In many tidal embayments, bottom patterns, such as the channel-shoal systems of the Wadden Sea, are observed. To gain understanding of the mechanisms that result in these bottom patterns, an idealized model is developed and analyzed for short tidal embayments. In this model, the water motion is

The Algorithm Theoretical Basis Document for Tidal Corrections

Science.gov (United States)

Fricker, Helen A.; Ridgway, Jeff R.; Minster, Jean-Bernard; Yi, Donghui; Bentley, Charles R.`

2012-01-01

This Algorithm Theoretical Basis Document deals with the tidal corrections that need to be applied to range measurements made by the Geoscience Laser Altimeter System (GLAS). These corrections result from the action of ocean tides and Earth tides which lead to deviations from an equilibrium surface. Since the effect of tides is dependent of the time of measurement, it is necessary to remove the instantaneous tide components when processing altimeter data, so that all measurements are made to the equilibrium surface. The three main tide components to consider are the ocean tide, the solid-earth tide and the ocean loading tide. There are also long period ocean tides and the pole tide. The approximate magnitudes of these components are illustrated in Table 1, together with estimates of their uncertainties (i.e. the residual error after correction). All of these components are important for GLAS measurements over the ice sheets since centimeter-level accuracy for surface elevation change detection is required. The effect of each tidal component is to be removed by approximating their magnitude using tidal prediction models. Conversely, assimilation of GLAS measurements into tidal models will help to improve them, especially at high latitudes.

The influence of role models in undergraduate nurse education.

Science.gov (United States)

Jack, Kirsten; Hamshire, Claire; Chambers, Alison

2017-12-01

To explore the concept of role modelling in undergraduate nurse education and its effect on the personal and professional development of student nurses. Effective educative strategies are important for student nurses, who have to cope with learning in both clinical and university settings. Given the contemporary issues facing nurse education and practice in the United Kingdom (UK), it is timely and important to undertake pedagogical research into the concept of role modelling as an effective educative method. A descriptive narrative approach. Unstructured interviews were conducted with 14 current/recently discontinued students from Adult and Mental Health branches of nursing degree programmes in the north-west region of England, United Kingdom (UK). Data were thematically analysed. Students valued exposure to positive role models in clinical and university settings and viewed them as beneficial to their learning. Exposure to negative role models occurred, and this provided students with opportunities to consider the type of nurse they aspired to become. In some cases, students' exposure to perceived poor practice had an adverse effect on their learning and led to negative feelings about nursing work. Clinical staff might be perceived as more relevant role models than those in the university setting although there were still opportunities for academic staff to model professional behaviours. The study found that role modelling is an effective way to support learning and led to student satisfaction across both clinical and university settings. The findings support the use of role models in nurse education, and further research about conscious positive modelling of practice is required. Exploring the use of role models is important when examining ways in which the quality of nurse education might be developed. © 2017 John Wiley & Sons Ltd.

Mixing methodology, nursing theory and research design for a practice model of district nursing advocacy.

Science.gov (United States)

Reed, Frances M; Fitzgerald, Les; Rae, Melanie

2016-01-01

To highlight philosophical and theoretical considerations for planning a mixed methods research design that can inform a practice model to guide rural district nursing end of life care. Conceptual models of nursing in the community are general and lack guidance for rural district nursing care. A combination of pragmatism and nurse agency theory can provide a framework for ethical considerations in mixed methods research in the private world of rural district end of life care. Reflection on experience gathered in a two-stage qualitative research phase, involving rural district nurses who use advocacy successfully, can inform a quantitative phase for testing and complementing the data. Ongoing data analysis and integration result in generalisable inferences to achieve the research objective. Mixed methods research that creatively combines philosophical and theoretical elements to guide design in the particular ethical situation of community end of life care can be used to explore an emerging field of interest and test the findings for evidence to guide quality nursing practice. Combining philosophy and nursing theory to guide mixed methods research design increases the opportunity for sound research outcomes that can inform a nursing model of care.

A formative model for student nurse development and evaluation

Directory of Open Access Journals (Sweden)

A. S. van der Merwe

1996-03-01

Full Text Available Preparing student nurses for the profession is a complex task for nurse educators; especially when dealing with the development of personal and interpersonal skills, qualities and values held in high esteem by the nursing profession and the community they serve. These researchers developed a model for formative evaluation of students by using the principles of inductive and deductive reasoning. This model was implemented in clinical practice situations and evaluated for its usefulness. It seems that the model enhanced the standards of nursing care because it had a positive effect on the behaviour of students and they were better motivated; the model also improved interpersonal relationships and communication between practising nurses and students.

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.

Mapping VIPS concepts for nursing interventions to the ISO reference terminology model for nursing actions: A collaborative Scandinavian analysis

DEFF Research Database (Denmark)

Ehnfors, Margareta; Angermo, Lilly Marit; Berring, Lene

2006-01-01

analyzed the VIPS model's concepts for nursing interventions using prototypical examples of nursing actions, involving 233 units of analyses, and collaborated in mapping the two models. All nursing interventions in the VIPS model comprise actions and targets, but a few lack explicit expressions of means......The aims of this study were to analyze the coherence between the concepts for nursing interventions in the Swedish VIPS model for nursing recording and the ISO Reference Terminology Model for Nursing Actions and to identify areas in the two models for further development. Seven Scandinavian experts....... In most cases, the recipient of care is implicit. Expressions for the aim of an action are absent from the ISO model. By this mapping we identified areas for future development of the VIPS model and the experience from nursing terminology work in Scandinavia can contribute to the international...

Soil Porewater Salinity Response to Sea-level Rise in Tidal Freshwater Forested Wetlands: A Modeling Study

Science.gov (United States)

Stagg, C. L.; Wang, H.; Krauss, K.; Conrads, P. A.; Swarzenski, C.; Duberstein, J. A.; DeAngelis, D.

2017-12-01

There is a growing concern about the adverse effects of salt water intrusion via tidal rivers and creeks into tidal freshwater forested wetlands (TFFWs) due to rising sea levels and reduction of freshwater flow. The distribution and composition of plant species, vegetation productivity, and biogeochemical functions including carbon sequestration capacity and flux rates in TFFWs have been found to be affected by increasing river and soil porewater salinities, with significant shifts occurring at a porewater salinity threshold of 3 PSU. However, the drivers of soil porewater salinity, which impact the health and ecological functions of TFFWs remains unclear, limiting our capability of predicting the future impacts of saltwater intrusion on ecosystem services provided by TFFWs. In this study, we developed a soil porewater salinity model for TFFWs based on an existing salt and water balance model with modifications to several key features such as the feedback mechanisms of soil salinity on evapotranspiration reduction and hydraulic conductivity. We selected sites along the floodplains of two rivers, the Waccamaw River (SC, USA) and the Savannah River (GA and SC, USA) that represent landscape salinity gradients of both surface water and soil porewater from tidal influence of the Atlantic Ocean. These sites represent healthy, moderately and highly salt-impacted forests, and oligohaline marshes. The soil porewater salinity model was calibrated and validated using field data collected at these sites throughout 2008-2016. The model results agreed well with field measurements. Analyses of the preliminary simulation results indicate that the magnitude, seasonal and annual variability, and duration of threshold salinities (e.g., 3 PSU) tend to vary significantly with vegetation status and type (i.e., healthy, degraded forests, and oligohaline marshes), especially during drought conditions. The soil porewater salinity model could be coupled with a wetland soil biogeochemistry

Thinking like a nurse: a research-based model of clinical judgment in nursing.

Science.gov (United States)

Tanner, Christine A

2006-06-01

This article reviews the growing body of research on clinical judgment in nursing and presents an alternative model of clinical judgment based on these studies. Based on a review of nearly 200 studies, five conclusions can be drawn: (1) Clinical judgments are more influenced by what nurses bring to the situation than the objective data about the situation at hand; (2) Sound clinical judgment rests to some degree on knowing the patient and his or her typical pattern of responses, as well as an engagement with the patient and his or her concerns; (3) Clinical judgments are influenced by the context in which the situation occurs and the culture of the nursing care unit; (4) Nurses use a variety of reasoning patterns alone or in combination; and (5) Reflection on practice is often triggered by a breakdown in clinical judgment and is critical for the development of clinical knowledge and improvement in clinical reasoning. A model based on these general conclusions emphasizes the role of nurses' background, the context of the situation, and nurses' relationship with their patients as central to what nurses notice and how they interpret findings, respond, and reflect on their response.

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

Joint Calibration of Submarine Groundwater Discharge (SGD) with Tidal Pumping: Modeling Variable-density Groundwater Flow in Unconfined Coastal Aquifer of Apalachee Bay, Gulf of Mexico

Science.gov (United States)

Li, X.; Hu, B.; Burnett, W.; Santos, I.

2008-05-01

Submarine Groundwater Discharge (SGD) as an unseen phenomenon is now recognized as an important pathway between land and sea. These discharges typically display significant spatial and temporal variability making quantification difficult. Groundwater seepage is patchy, diffuse, and temporally variable, and thus makes the estimation of its magnitude and components is a challenging enterprise. A two-dimensional hydrogeological model is developed to the near-shore environment of an unconfined aquifer at a Florida coastal area in the northeastern Gulf of Mexico. Intense geological survey and slug tests are set to investigate the heterogeneity of this layered aquifer. By applying SEAWAT2000, considering the uncertainties caused by changes of boundary conditions, a series of variable-density-flow models incorporates the tidal-influenced seawater recirculation and the freshwater-saltwater mixing zone under the dynamics of tidal pattern, tidal amplitude and variation of water table. These are thought as the contributing factors of tidal pumping and hydraulic gradient which are the driven forces of SGD. A tidal-influenced mixing zone in the near-shore aquifer shows the importance of tidal mechanism to flow and salt transport in the process of submarine pore water exchange. Freshwater ratio in SGD is also analyzed through the comparison of Submarine Groundwater Recharge and freshwater inflow. The joint calibration with other methods (natural tracer model and seepage meter) is also discussed.

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

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.

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

Nursing research and bibliographic citation models.

Science.gov (United States)

Angordans, Jordi Piqué; Puig, Ramón Camaño; Noguera, Carmen Piqué

2009-01-01

This research focuses on the analysis of how nursing journals publish their papers. Basically, two models are analyzed, Vancouver, by the International Committee of Medical Journal Editors, and APA by the American Psychological Association. Their advantages and disadvantages are discussed. In view of how research papers are currently published and how research is judged, the authors propose that nursing journals adopt their own model, irrespective of how medical professionals publish.

Proposal of a theoretical model for the practical nurse

Directory of Open Access Journals (Sweden)

Dolores Abril Sabater

2010-01-01

Full Text Available AIM: To determine which model of nursing is proposed by care professionals and the reason for their choice. METHOD: cross-sectional, descriptive study design. The main variable: Nursing Models and Theories. As secondary variables were collected: age, gender, years of work experience, nursing model of basic training, and course/s related. We used a self-elaborated, anonymous questionnaire, passed between April - May, 2006. Not random sample.RESULTS: 546 nurses were invited, answered 205. 38 % response rate. Virginia Henderson was the more selected model (33%, however, 42% left the question blank, 12% indicated that they wanted to work under the guidance of a model. They selected a specifically model: Knowledge of the model to their training, standardization in other centers, the characteristics of the model itself and identification with its philosophy. They are not decided by a model by ignorance, lack of time and usefulness. CONCLUSIONS: The model chosen mostly for their daily work was Virginia Henderson model, so that knowledge of a model is the main reason for their election. Professionals who choose not to use the model in their practice realize offers and calling for resources, besides to explain the lack of knowledge on this topic. To advance the nursing profession is necessary that nurse is thought over widely on the abstract concepts of the theory in our context.

Tidal-induced large-scale regular bed form patterns in a three-dimensional shallow water model

NARCIS (Netherlands)

Hulscher, Suzanne J.M.H.

1996-01-01

The three-dimensional model presented in this paper is used to study how tidal currents form wave-like bottom patterns. Inclusion of vertical flow structure turns out to be necessary to describe the formation, or absence, of all known large-scale regular bottom features. The tide and topography are

Potential environmental impact of tidal energy extraction in the Pentland Firth at large spatial scales: results of a biogeochemical model

Science.gov (United States)

van der Molen, Johan; Ruardij, Piet; Greenwood, Naomi

2016-05-01

A model study was carried out of the potential large-scale (> 100 km) effects of marine renewable tidal energy generation in the Pentland Firth, using the 3-D hydrodynamics-biogeochemistry model GETM-ERSEM-BFM. A realistic 800 MW scenario and a high-impact scenario with massive expansion of tidal energy extraction to 8 GW scenario were considered. The realistic 800 MW scenario suggested minor effects on the tides, and undetectable effects on the biogeochemistry. The massive-expansion 8 GW scenario suggested effects would be observed over hundreds of kilometres away with changes of up to 10 % in tidal and ecosystem variables, in particular in a broad area in the vicinity of the Wash. There, waters became less turbid, and primary production increased with associated increases in faunal ecosystem variables. Moreover, a one-off increase in carbon storage in the sea bed was detected. Although these first results suggest positive environmental effects, further investigation is recommended of (i) the residual circulation in the vicinity of the Pentland Firth and effects on larval dispersal using a higher-resolution model and (ii) ecosystem effects with (future) state-of-the-art models if energy extraction substantially beyond 1 GW is planned.

Long-Period Tidal Variations in the Length of Day

Science.gov (United States)

Ray, Richard D.; Erofeeva, Svetlana Y.

2014-01-01

A new model of long-period tidal variations in length of day is developed. The model comprises 80 spectral lines with periods between 18.6 years and 4.7 days, and it consistently includes effects of mantle anelasticity and dynamic ocean tides for all lines. The anelastic properties followWahr and Bergen; experimental confirmation for their results now exists at the fortnightly period, but there remains uncertainty when extrapolating to the longest periods. The ocean modeling builds on recent work with the fortnightly constituent, which suggests that oceanic tidal angular momentum can be reliably predicted at these periods without data assimilation. This is a critical property when modeling most long-period tides, for which little observational data exist. Dynamic ocean effects are quite pronounced at shortest periods as out-of-phase rotation components become nearly as large as in-phase components. The model is tested against a 20 year time series of space geodetic measurements of length of day. The current international standard model is shown to leave significant residual tidal energy, and the new model is found to mostly eliminate that energy, with especially large variance reduction for constituents Sa, Ssa, Mf, and Mt.

A model for mentoring newly-appointed nurse educators in nursing education institutions in South Africa.

Science.gov (United States)

Seekoe, Eunice

2014-04-24

South Africa transformed higher education through the enactment of the Higher Education Act (No. 101 of 1997). The researcher identified the need to develop a model for the mentoring of newly-appointed nurse educators in nursing education institutions in South Africa.  To develop and describe the model for mentoring newly-appointed nurse educators in nursing education institutions in South Africa.  A qualitative and theory-generating design was used (following empirical findings regarding needs analysis) in order to develop the model. The conceptualisation of the framework focused on the context, content, process and the theoretical domains that influenced the model. Ideas from different theories were borrowed from and integrated with the literature and deductive and inductive strategies were applied.  The structure of the model is multidimensional and complex in nature (macro, mesoand micro) based on the philosophy of reflective practice, competency-based practice andcritical learning theories. The assumptions are in relation to stakeholders, context, mentoring, outcome, process and dynamic. The stakeholders are the mentor and mentee within an interactive participatory relationship. The mentoring takes place within the process with a sequence of activities such as relationship building, development, engagement, reflective process and assessment. Capacity building and empowerment are outcomes of mentoring driven by motivation.  The implication for nurse managers is that the model can be used to develop mentoring programmes for newly-appointed nurse educators.

[Evaluation of tidal volume delivered by ventilators during volume-controlled ventilation].

Science.gov (United States)

Zhou, Juan; Yan, Yong; Cao, Desen

2014-12-01

To study the ways which ensure the delivery of enough tidal volume to patients under various conditions close to the demand of the physician. The volume control ventilation model was chosen, and the simulation lung type was active servo lung ASL 5000 or Michigan lung 1601. The air resistance, air compliance and lung type in simulation lungs were set. The tidal volume was obtained from flow analyzer PF 300. At the same tidal volume, the displaying values of tidal volume of E5, Servo i, Evital 4, and Evital XL ventilators with different lung types of patient, compliance of gas piping, leakage, gas types, etc. were evaluated. With the same setting tidal volume of a same ventilator, the tidal volume delivered to patients was different with different lung types of patient, compliance of gas piping, leakage, gas types, etc. Reducing compliance and increasing resistance of the patient lungs caused high peak airway pressure, the tidal volume was lost in gas piping, and the tidal volume be delivered to the patient lungs was decreased. If the ventilator did not compensate to leakage, the tidal volume delivered to the patient lungs was decreased. When the setting gas type of ventilator did not coincide with that applying to the patient, the tidal volume be delivered to the patient lungs might be different with the setting tidal volume of ventilator. To ensure the delivery of enough tidal volume to patients close to the demand of the physician, containable factors such as the compliance of gas piping, leakage, and gas types should be controlled.

Modelling the dispersion of non-conservative radionuclides in tidal waters. Pt. 1: Conceptual and mathematical model

International Nuclear Information System (INIS)

Perianez, R.; Abril, J.M.; Garcia-Leon, M.

1996-01-01

A 2D four-phase model to study the dispersion of non-conservative radionuclides in tidal waters, in conditions of disequilibrium for ionic exchanges, has been developed. At disequilibrium conditions, ionic exchanges cannot be formulated using distribution coefficients k d . Thus, kinetic transfer coefficients have been used. The model includes ionic exchanges among water and the solid phases (suspended matter and two grain size fractions of sediments), the deposition and resuspension of suspended matter and advective plus diffusive transport. In the second part of this work, which is presented in a separate paper, the model is applied to simulate 226 Ra dispersion, discharged from a fertilizer processing plant, in an estuarine system in the south-west of Spain. (Author)

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.

Integrating nursing diagnostic concepts into the medical entities dictionary using the ISO Reference Terminology Model for Nursing Diagnosis.

Science.gov (United States)

Hwang, Jee-In; Cimino, James J; Bakken, Suzanne

2003-01-01

The purposes of the study were (1) to evaluate the usefulness of the International Standards Organization (ISO) Reference Terminology Model for Nursing Diagnoses as a terminology model for defining nursing diagnostic concepts in the Medical Entities Dictionary (MED) and (2) to create the additional hierarchical structures required for integration of nursing diagnostic concepts into the MED. The authors dissected nursing diagnostic terms from two source terminologies (Home Health Care Classification and the Omaha System) into the semantic categories of the ISO model. Consistent with the ISO model, they selected Focus and Judgment as required semantic categories for creating intensional definitions of nursing diagnostic concepts in the MED. Because the MED does not include Focus and Judgment hierarchies, the authors developed them to define the nursing diagnostic concepts. The ISO model was sufficient for dissecting the source terminologies into atomic terms. The authors identified 162 unique focus concepts from the 266 nursing diagnosis terms for inclusion in the Focus hierarchy. For the Judgment hierarchy, the authors precoordinated Judgment and Potentiality instead of using Potentiality as a qualifier of Judgment as in the ISO model. Impairment and Alteration were the most frequently occurring judgments. Nursing care represents a large proportion of health care activities; thus, it is vital that terms used by nurses are integrated into concept-oriented terminologies that provide broad coverage for the domain of health care. This study supports the utility of the ISO Reference Terminology Model for Nursing Diagnoses as a facilitator for the integration process.

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...

Modelling of tidal hydrodynamics for a tropical ecosystem with implications for pollutant dispersion (Cochin Estuary, Southwest India)

Digital Repository Service at National Institute of Oceanography (India)

Balachandran, K.K.; Reddy, G.S.; Revichandran, C.; Srinivas, K.; Vijayan, P.R.; Thottam, T.J.

Tidal circulation in the Cochin Estuary, a moderately polluted estuary along the southwest coast of India, was studied using a 2D hydrodynamic model. The predicted tides and currents showed very good agreement with measured tides. Particle...

Tidal disruption of asteroids by supermassive black holes

Directory of Open Access Journals (Sweden)

Gomboc A.

2012-12-01

Full Text Available The compact radio source Sgr A* at the centre of our Galaxy harbours a super-massive black hole, and is therefore the nearest laboratory for testing the super-massive black hole astrophysics and environment. Since it is not an active galactic nucleus, it also offers the possibility of observing the capture of low-mass objects, such as comets or asteroids, that may orbit the central black hole. In this paper we discuss conditions for tidal disruption of low-mass objects and predictions of the appearance and light curve of such events, as well as their relevance for the X-ray and infra-red flares detected in Sgr A*. The modelled light curves of such tidal disruption events bear marks of the strong gravitational field: tidal squeezing and elongation of the object, gravitational lensing, aberration of light, and Doppler effects. Finally, we show that this model is able to reproduce and fit X-ray flares.

The influence of neap-spring tidal variation and wave energy on sediment flux in salt marsh tidal creeks

Science.gov (United States)

Lacy, Jessica; Ferner, Matthew C.; Callaway, John C.

2018-01-01

Sediment flux in marsh tidal creeks is commonly used to gage sediment supply to marshes. We conducted a field investigation of temporal variability in sediment flux in tidal creeks in the accreting tidal marsh at China Camp State Park adjacent to northern San Francisco Bay. Suspended-sediment concentration (SSC), velocity, and depth were measured near the mouths of two tidal creeks during three six-to-ten-week deployments: two in winter and one in summer. Currents, wave properties and SSC were measured in the adjacent shallows. All deployments spanned the largest spring tides of the season. Results show that tidally-averaged suspended-sediment flux (SSF) in the tidal creeks decreased with increasing tidal energy, and SSF was negative (bayward) for tidal cycles with maximum water surface elevation above the marsh plain. Export during the largest spring tides dominated the cumulative SSF measured during the deployments. During ebb tides following the highest tides, velocities exceeded 1 m/s in the narrow tidal creeks, resulting in negative tidally-averaged water flux, and mobilizing sediment from the creek banks or bed. Storm surge also produced negative SSF. Tidally-averaged SSF was positive in wavey conditions with moderate tides. Spring-tide sediment export was about 50% less at a station 130 m further up the tidal creek than at the creek mouth. The negative tidally-averaged water flux near the creek mouth during spring tides indicates that in the lower marsh, some of the water flooding directly across the bay--marsh interface drains through the tidal creeks, and suggests that this interface may be a pathway for sediment supply to the lower marsh as well.

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

A model for mentoring newly-appointed nurse educators in nursing education institutions in South Africa

Directory of Open Access Journals (Sweden)

Eunice Seekoe

2014-02-01

Full Text Available Background: South Africa transformed higher education through the enactment of the Higher Education Act (No. 101 of 1997. The researcher identified the need to develop a model for the mentoring of newly-appointed nurse educators in nursing education institutions in South Africa. Objectives: To develop and describe the model for mentoring newly-appointed nurse educators in nursing education institutions in South Africa. Method: A qualitative and theory-generating design was used (following empirical findings regarding needs analysis in order to develop the model. The conceptualisation of the framework focused on the context, content, process and the theoretical domains that influenced the model. Ideas from different theories were borrowed from and integrated with the literature and deductive and inductive strategies were applied. Results: The structure of the model is multidimensional and complex in nature (macro, mesoand micro based on the philosophy of reflective practice, competency-based practice andcritical learning theories. The assumptions are in relation to stakeholders, context, mentoring, outcome, process and dynamic. The stakeholders are the mentor and mentee within an interactive participatory relationship. The mentoring takes place within the process with a sequence of activities such as relationship building, development, engagement, reflective process and assessment. Capacity building and empowerment are outcomes of mentoring driven by motivation. Conclusion: The implication for nurse managers is that the model can be used to develop mentoring programmes for newly-appointed nurse educators.

An ontology model for nursing narratives with natural language generation technology.

Science.gov (United States)

Min, Yul Ha; Park, Hyeoun-Ae; Jeon, Eunjoo; Lee, Joo Yun; Jo, Soo Jung

2013-01-01

The purpose of this study was to develop an ontology model to generate nursing narratives as natural as human language from the entity-attribute-value triplets of a detailed clinical model using natural language generation technology. The model was based on the types of information and documentation time of the information along the nursing process. The typesof information are data characterizing the patient status, inferences made by the nurse from the patient data, and nursing actions selected by the nurse to change the patient status. This information was linked to the nursing process based on the time of documentation. We describe a case study illustrating the application of this model in an acute-care setting. The proposed model provides a strategy for designing an electronic nursing record system.

A parametric model for the changes in the complex valued conductivity of a lung during tidal breathing

Science.gov (United States)

Nordebo, Sven; Dalarsson, Mariana; Khodadad, Davood; Müller, Beat; Waldman, Andreas D.; Becher, Tobias; Frerichs, Inez; Sophocleous, Louiza; Sjöberg, Daniel; Seifnaraghi, Nima; Bayford, Richard

2018-05-01

Classical homogenization theory based on the Hashin–Shtrikman coated ellipsoids is used to model the changes in the complex valued conductivity (or admittivity) of a lung during tidal breathing. Here, the lung is modeled as a two-phase composite material where the alveolar air-filling corresponds to the inclusion phase. The theory predicts a linear relationship between the real and the imaginary parts of the change in the complex valued conductivity of a lung during tidal breathing, and where the loss cotangent of the change is approximately the same as of the effective background conductivity and hence easy to estimate. The theory is illustrated with numerical examples based on realistic parameter values and frequency ranges used with electrical impedance tomography (EIT). The theory may be potentially useful for imaging and clinical evaluations in connection with lung EIT for respiratory management and control.

An idealized model of tidal dynamics in the North Sea: resonance proporties and response to large-scale changes

NARCIS (Netherlands)

Roos, Pieter C.; Velema, Jorick J.; Hulscher, Suzanne J.M.H.; Stolk, Ad

2011-01-01

An idealized process-based model is developed to investigate tidal dynamics in the North Sea. The model geometry consists of a sequence of different rectangular compartments of uniform depth, thus, accounting for width and depth variations in a stepwise manner. This schematization allows for a quick

Postgraduate education for nurses: the Middlesex model.

Science.gov (United States)

Caldwell, K

2001-04-01

Nurse education has been subject to many changes and much debate and criticism over recent years. What has become increasingly evident is that with the changing nature of nursing within society, nursing curricula have to be more flexible and dynamic if they are to meet a multiplicity of needs. There is also a need to recognize that many levels of curricula will be required to prepare the nurses of the future. At Middlesex University the development of specialist practice programmes at postgraduate diploma level, and preparation of nurses for a higher level of practice at masters level has required the development of a new curriculum model which allows both the individualization of academic programmes to meet the needs of nurses, their clients and the organization in which they work, and the integration of development and learning through practice. This model is built on the results of an evaluation of an existing postgraduate programme in interprofessional health care. Key features of the curriculum development include a structured collaboration between student, practice mentor and academic supervisor, and the use of a professional development portfolio to individualize the academic programme and facilitate autonomous learning. Copyright 2001 Harcourt Publishers Ltd.

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...

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)

Forecasting tidal marsh elevation and habitat change through fusion of Earth observations and a process model

Science.gov (United States)

Byrd, Kristin B.; Windham-Myers, Lisamarie; Leeuw, Thomas; Downing, Bryan D.; Morris, James T.; Ferner, Matthew C.

2016-01-01

Reducing uncertainty in data inputs at relevant spatial scales can improve tidal marsh forecasting models, and their usefulness in coastal climate change adaptation decisions. The Marsh Equilibrium Model (MEM), a one-dimensional mechanistic elevation model, incorporates feedbacks of organic and inorganic inputs to project elevations under sea-level rise scenarios. We tested the feasibility of deriving two key MEM inputs—average annual suspended sediment concentration (SSC) and aboveground peak biomass—from remote sensing data in order to apply MEM across a broader geographic region. We analyzed the precision and representativeness (spatial distribution) of these remote sensing inputs to improve understanding of our study region, a brackish tidal marsh in San Francisco Bay, and to test the applicable spatial extent for coastal modeling. We compared biomass and SSC models derived from Landsat 8, DigitalGlobe WorldView-2, and hyperspectral airborne imagery. Landsat 8-derived inputs were evaluated in a MEM sensitivity analysis. Biomass models were comparable although peak biomass from Landsat 8 best matched field-measured values. The Portable Remote Imaging Spectrometer SSC model was most accurate, although a Landsat 8 time series provided annual average SSC estimates. Landsat 8-measured peak biomass values were randomly distributed, and annual average SSC (30 mg/L) was well represented in the main channels (IQR: 29–32 mg/L), illustrating the suitability of these inputs across the model domain. Trend response surface analysis identified significant diversion between field and remote sensing-based model runs at 60 yr due to model sensitivity at the marsh edge (80–140 cm NAVD88), although at 100 yr, elevation forecasts differed less than 10 cm across 97% of the marsh surface (150–200 cm NAVD88). Results demonstrate the utility of Landsat 8 for landscape-scale tidal marsh elevation projections due to its comparable performance with the other sensors

Sedimentation and response to sea-level rise of a restored marsh with reduced tidal exchange: Comparison with a natural tidal marsh

Science.gov (United States)

Vandenbruwaene, W.; Maris, T.; Cahoon, D.R.; Meire, P.; Temmerman, S.

2011-01-01

Along coasts and estuaries, formerly embanked land is increasingly restored into tidal marshes in order to re-establish valuable ecosystem services, such as buffering against flooding. Along the Scheldt estuary (Belgium), tidal marshes are restored on embanked land by allowing a controlled reduced tide (CRT) into a constructed basin, through a culvert in the embankment. In this way tidal water levels are significantly lowered (ca. 3 m) so that a CRT marsh can develop on formerly embanked land with a ca. 3 m lower elevation than the natural tidal marshes. In this study we compared the long-term change in elevation (ΔE) within a CRT marsh and adjacent natural tidal marsh. Over a period of 4 years, the observed spatio-temporal variations in ΔE rate were related to variations in inundation depth, and this relationship was not significantly different for the CRT marsh and natural tidal marsh. A model was developed to simulate the ΔE over the next century. (1) Under a scenario without mean high water level (MHWL) rise in the estuary, the model shows that the marsh elevation-ΔE feedback that is typical for a natural tidal marsh (i.e. rising marsh elevation results in decreasing inundation depth and therefore a decreasing increase in elevation) is absent in the basin of the CRT marsh. This is because tidal exchange of water volumes between the estuary and CRT marsh are independent from the CRT marsh elevation but dependent on the culvert dimensions. Thus the volume of water entering the CRT remains constant regardless of the marsh elevation. Consequently the CRT MHWL follows the increase in CRT surface elevation, resulting after 75 years in a 2–2.5 times larger elevation gain in the CRT marsh, and a faster reduction of spatial elevation differences. (2) Under a scenario of constant MHWL rise (historical rate of 1.5 cm a-1), the equilibrium elevation (relative to MHWL) is 0.13 m lower in the CRT marsh and is reached almost 2 times faster. (3) Under a scenario of

Which future for the tidal sector in France? Towards a new model of territorial development

International Nuclear Information System (INIS)

Aelbrecht, Denis; Deroo, Luc; Le Visage, Christophe; Rabain, Antoine

2017-01-01

This document proposes a brief overview of works by a French national work-group of the SHF (French Hydro-technical Society) on the new tidal sector. It indicates recent and current development in the renewable marine energy sector: offshore wind farms along the French coasts, floating wind energy demonstrators, several tidal stream demonstrators, and other projects. British projects are also evoked. Then various aspects which could be success factors, are briefly discussed: the tidal potential, project configuration types (dams in estuary, coastal lagoons, offshore lagoons), interactions with the environment (sea and coastal ecosystems, sediments), opportunities of technological innovation (belt of the tidal basin, machine technology, exploitation mode), the concept of tidal garden, economic performance and viability (orientations for cost reduction and income increase). The issue of feasibility with respect with the NIMBY syndrome is finally addressed, and orientations and principles are briefly defined to evolve towards a YINBY (Yes in my back yard) syndrome

Assessment of tidal range energy resources based on flux conservation in Jiantiao Bay, China

Science.gov (United States)

Du, Min; Wu, He; Yu, Huaming; Lv, Ting; Li, Jiangyu; Yu, Yujun

2017-12-01

La Rance Tidal Range Power Station in France and Jiangxia Tidal Range Power Station in China have been both long-term successful commercialized operations as kind of role models for public at large for more than 40 years. The Sihwa Lake Tidal Range Power Station in South Korea has also developed to be the largest marine renewable power station with its installed capacity 254 MW since 2010. These practical applications prove that the tidal range energy as one kind of marine renewable energy exploitation and utilization technology is becoming more and more mature and it is used more and more widely. However, the assessment of the tidal range energy resources is not well developed nowadays. This paper summarizes the main problems in tidal range power resource assessment, gives a brief introduction to tidal potential energy theory, and then we present an analyzed and estimated method based on the tide numerical modeling. The technical characteristics and applicability of these two approaches are compared with each other. Furthermore, based on the theory of tidal range energy generation combined with flux conservation, this paper proposes a new assessment method that include a series of evaluation parameters and it can be easily operated to calculate the tidal range energy of the sea. Finally, this method is applied on assessment of the tidal range power energy of the Jiantiao Harbor in Zhejiang Province, China for demonstration and examination.

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.

Ice-Shelf Flexure and Tidal Forcing of Bindschadler Ice Stream, West Antarctica

Science.gov (United States)

Walker, Ryan T.; Parizek, Bryron R.; Alley, Richard B.; Brunt, Kelly M.; Anandakrishnan, Sridhar

2014-01-01

Viscoelastic models of ice-shelf flexure and ice-stream velocity perturbations are combined into a single efficient flowline model to study tidal forcing of grounded ice. The magnitude and timing of icestream response to tidally driven changes in hydrostatic pressure and/or basal drag are found to depend significantly on bed rheology, with only a perfectly plastic bed allowing instantaneous velocity response at the grounding line. The model can reasonably reproduce GPS observations near the grounding zone of Bindschadler Ice Stream (formerly Ice Stream D) on semidiurnal time scales; however, other forcings such as tidally driven ice-shelf slope transverse to the flowline and flexurally driven till deformation must also be considered if diurnal motion is to be matched

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.

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 ...

Tidal energy

International Nuclear Information System (INIS)

Lochte, H.G.

1995-01-01

Together with wave energy, ocean thermal energy, and the often overlooked energy from ocean curents tidal energy belongs to those renewable energy sources that can be subsumed under the generic term of ocean energy. All that these energy sources have in common, however, is that they are found in the ocean. The present article discusses tidal energy with respect to the four principal factors determining the scope of a renewable energy source, namely global, technical, and economic availability and ecological acceptability. (orig.) [de

Certified Nursing Assistants’ Explanatory Models of Nursing Home Resident Depression

OpenAIRE

Piven, Mary Lynn; Anderson, Ruth A.; Colón-Emeric, Cathleen S.; Sandelowski, Margarete

2008-01-01

In this study, we explored how Certified Nursing Assistants (CNAs) understood resident depression. Interviews with 18 CNAs, working in two nursing homes were guided by Kleinman’s Explanatory Models of Illness framework. Interview data were content analyzed and CNAs’ descriptions of depression were compared to the MDS 2.0 Mood Screen and to DSM-IV-TR Depression Criteria. CNAs identified causes, signs, and symptoms of depression, but they were unsure about the duration and normalcy of depressio...

Empirical models of Jupiter's interior from Juno data. Moment of inertia and tidal Love number k2

Science.gov (United States)

Ni, Dongdong

2018-05-01

Context. The Juno spacecraft has significantly improved the accuracy of gravitational harmonic coefficients J4, J6 and J8 during its first two perijoves. However, there are still differences in the interior model predictions of core mass and envelope metallicity because of the uncertainties in the hydrogen-helium equations of state. New theoretical approaches or observational data are hence required in order to further constrain the interior models of Jupiter. A well constrained interior model of Jupiter is helpful for understanding not only the dynamic flows in the interior, but also the formation history of giant planets. Aims: We present the radial density profiles of Jupiter fitted to the Juno gravity field observations. Also, we aim to investigate our ability to constrain the core properties of Jupiter using its moment of inertia and tidal Love number k2 which could be accessible by the Juno spacecraft. Methods: In this work, the radial density profile was constrained by the Juno gravity field data within the empirical two-layer model in which the equations of state are not needed as an input model parameter. Different two-layer models are constructed in terms of core properties. The dependence of the calculated moment of inertia and tidal Love number k2 on the core properties was investigated in order to discern their abilities to further constrain the internal structure of Jupiter. Results: The calculated normalized moment of inertia (NMOI) ranges from 0.2749 to 0.2762, in reasonable agreement with the other predictions. There is a good correlation between the NMOI value and the core properties including masses and radii. Therefore, measurements of NMOI by Juno can be used to constrain both the core mass and size of Jupiter's two-layer interior models. For the tidal Love number k2, the degeneracy of k2 is found and analyzed within the two-layer interior model. In spite of this, measurements of k2 can still be used to further constrain the core mass and size

Modelling the effect of suspended load transport and tidal asymmetry on the equilibrium tidal sand wave height

NARCIS (Netherlands)

van Gerwen, W.; Borsje, Bastiaan Wijnand; Damveld, Johan Hendrik; Hulscher, Suzanne J.M.H.

2018-01-01

Tidal sand waves are rhythmic bed forms found in shallow sandy coastal seas, reaching heights up to ten meters and migration rates of several meters per year. Because of their dynamic behaviour, unravelling the physical processes behind the growth of these bed forms is of particular interest to

In search of a Croatian model of nursing education.

Science.gov (United States)

Simunovic, Vladimir J; Zupanovic, Marija; Mihanovic, Frane; Zemunik, Tatijana; Bradaric, Nikola; Jankovic, Stipan

2010-10-01

To analyze the present status and ongoing reforms of nursing education in Europe, to compare it with the situation in Croatia, and to propose a new educational model that corresponds to the needs of the Croatian health care system. The literature on contemporary nursing education in Europe and North America was reviewed, together with European Commission directives and regulations, as well as pertinent World Health Organization documents. In addition, 20 recent annual reports from 2003-2009, submitted by national nursing associations to the Workgroup of European Nurse Researchers (WERN), were studied. After appraisal of current trends, the Working Group on Reform of Nursing Education drafted The Croatian Model for Education in Nursing and developed a three-cycle curriculum with syllabus. The proposed curriculum is radically different from traditional ones. Responding to modern demands, it focuses on outcomes (developing competencies) and is evidence-based. A new, Croatian concept of nursing education is presented that is concordant with reforms in nursing education in other European countries. It holds promise for making nursing education an integral part of a unified European system of higher education.

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

Tidal Turbines’ Layout in a Stream with Asymmetry and Misalignment

Directory of Open Access Journals (Sweden)

Nicolas Guillou

2017-11-01

Full Text Available A refined assessment of tidal currents variability is a prerequisite for successful turbine deployment in the marine environment. However, the numerical evaluation of the tidal kinetic energy resource relies, most of the time, on integrated parameters, such as the averaged or maximum stream powers. Predictions from a high resolution three-dimensional model are exploited here to characterize the asymmetry and misalignment between the flood and ebb tidal currents in the “Raz de Sein”, a strait off western Brittany (France with strong potential for array development. A series of parameters is considered to assess resource variability and refine the cartography of local potential tidal stream energy sites. The strait is characterized by strong tidal flow divergence with currents’ asymmetry liable to vary output power by 60% over a tidal cycle. Pronounced misalignments over 20 ∘ are furthermore identified in a great part of energetic locations, and this may account for a deficit of the monthly averaged extractable energy by more than 12%. As sea space is limited for turbines, it is finally suggested to aggregate flood and ebb-dominant stream powers on both parts of the strait to output energy with reduced asymmetry.

Promoting Excellence in Nursing Education (PENE): Pross evaluation model.

Science.gov (United States)

Pross, Elizabeth A

2010-08-01

The purpose of this article is to examine the Promoting Excellence in Nursing Education (PENE) Pross evaluation model. A conceptual evaluation model, such as the one described here, may be useful to nurse academicians in the ongoing evaluation of educational programs, especially those with goals of excellence. Frameworks for evaluating nursing programs are necessary because they offer a way to systematically assess the educational effectiveness of complex nursing programs. This article describes the conceptual framework and its tenets of excellence. Copyright 2009 Elsevier Ltd. All rights reserved.

Washington State Nursing Home Administrator Model Curriculum. Final Report.

Science.gov (United States)

Cowan, Florence Kelly

The course outlines presented in this final report comprise a proposed Fort Steilacoom Community College curriculum to be used as a statewide model two-year associate degree curriculum for nursing home administrators. The eight courses described are introduction to nursing, home administration, financial management of nursing homes, nursing home…

Reconstructing marginality: a new model of cultural diversity in nursing.

Science.gov (United States)

Southwick, Margaret; Polaschek, Nick

2014-05-01

This article presents a new model of cultural diversity in nursing that critically reconstructs the concept of marginality that underpins other models. Rather than viewing the marginal as "other," marginality is redefined as the space in between the dominant cultural reality and the cultural realities of minority groups located within a society. Members of a minority cultural group who become skilled in the difficult process of negotiating this in-between space open the possibility of transformation within nursing education and practice. This model has been applied in a study of the experience of nursing students of Pacific ethnicity in New Zealand. Subsequently, an undergraduate Pacific nursing program was developed, with greatly increased success rates in registration of Pacific nurses. This model of cultural diversity can also be used to understand nursing practice involving people from minority cultures or other socially excluded categories. Copyright 2014, SLACK Incorporated.

Mapping VIPS Concepts for Nursing Interventions to the ISO Reference Terminology Model for Nursing Actions: A Collaborative Scandinavian Analysis

DEFF Research Database (Denmark)

Lauge Berring, Lene; Ehnfors, Margareta; Angermo, Lilly

2005-01-01

The aims of this study were to analyze the coherence between the concepts for nursing interventions in the Swedish VIPS model for nursing recording and the ISO Reference Terminology Model for Nursing Actions and to identify areas in the two models for further development. Seven Scandinavian experts...

Initial formation of channels and shoals in a short tidal embayment

NARCIS (Netherlands)

Schuttelaars, H.M.; Swart, H.E. de

1997-01-01

It is demonstrated by using a simple model that bedforms in a short tidal embayment can develop due to a positive feedback between tidal currents sediment transport and bedforms The system is forced by a prescribed free surface elevations at the entrance of the embayment The water motions are

Cultural boundary surfing in mental health nursing: a creative narration.

Science.gov (United States)

Kidd, Jacquie

2010-01-01

In the mental health context, nurses navigate multifaceted boundaries every day in an effort to develop and maintain the therapeutic relationship; an endeavour that is breathtaking in its complexity. In this paper, I adopt an unconventional form of writing to explore the individual nature of cultural boundaries, and uncover hidden messages that impact on our efforts to build connections across cultures and ethnicities in mental health settings. Presented as a play, the conversation between protagonists explores cultural competence alongside the notion of 'discovery', and the potential of the Tidal Model to provide a vehicle for successful cultural boundary surfing.

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.

THE EFFECT OF MASS LOSS ON THE TIDAL EVOLUTION OF EXTRASOLAR PLANET

International Nuclear Information System (INIS)

Guo, J. H.

2010-01-01

By combining mass loss and tidal evolution of close-in planets, we present a qualitative study on their tidal migrations. We incorporate mass loss in tidal evolution for planets with different masses and find that mass loss could interfere with tidal evolution. In an upper limit case (β = 3), a significant portion of mass may be evaporated in a long evolution timescale. Evidence of greater modification of the planets with an initial separation of about 0.1 AU than those with a = 0.15 AU can be found in this model. With the assumption of a large initial eccentricity, the planets with initial mass ≤1 M J and initial distance of about 0.1 AU could not survive. With the supposition of β = 1.1, we find that the loss process has an effect on the planets with low mass at a ∼ 0.05 AU. In both cases, the effect of evaporation on massive planets can be neglected. Also, heating efficiency and initial eccentricity have significant influence on tidal evolution. We find that even low heating efficiency and initial eccentricity have a significant effect on tidal evolution. Our analysis shows that evaporation on planets with different initial masses can accelerate (decelerate) the tidal evolution due to the increase (decrease) in tide of the planet (star). Consequently, the effect of evaporation cannot be neglected in evolutionary calculations of close-in planets. The physical parameters of HD 209458b can be fitted by our model.

A model of adaptation of overseas nurses: exploring the experiences of Japanese nurses working in Australia.

Science.gov (United States)

Kishi, Yuka; Inoue, Kumiyo; Crookes, Patrick; Shorten, Allison

2014-04-01

The purpose of the study was to investigate the experiences of Japanese nurses and their adaptation to their work environment in Australia. Using a qualitative research method and semistructured interviews, the study aimed to discover, describe, and analyze the experiences of 14 Japanese nurses participating in the study. A qualitative study. Fourteen Japanese registered nurses working in Australian hospitals participated in the study. Individual semistructured interviews were conducted from April to June in 2008. Thematic analysis was used to identify themes within the data. Analysis of qualitative open-ended questions revealed the participants' adaptation process. It consists of three themes or phases: seeking (S), acclimatizing (A), and settling (S), subsequently named the S.A.S. model. The conceptual model of the adaptation processes of 14 Japanese nurses working in Australia includes the seeking, acclimatizing, and settling phases. Although these phases are not mutually exclusive and the process is not necessarily uniformly linear, all participants in this study passed through this S.A.S. model in order to adapt to their new environment. The S.A.S. model of adaptation helps to describe the experiences of Japanese overseas qualified nurses working in Australian hospitals. Future research is needed to examine whether this model can be applied to nurses from other countries and in other settings outside Australia.

Numerical modelling to assess maintenance strategy management options for a small tidal inlet

Science.gov (United States)

Shaeri, Saeed; Tomlinson, Rodger; Etemad-Shahidi, Amir; Strauss, Darrell

2017-03-01

Small tidal inlets are found to be more sensitive to anthropogenic alteration than their larger counterparts. Such alterations, although typically supported by technical design reports, sometimes require amendments or modification. One of the most suitable tools to conduct the necessary studies in this regard is numerical modelling, since the behaviour of the inlet system in response to proposed remedial actions, can easily be identified. In this paper, various alternative proposals are investigated to determine the most practical and viable option to mitigate the need for ongoing maintenance at a typical small, jettied tidal inlet. The main tool to investigate the alternatives is the hydro-sedimentological modelling of the inlet system, which was performed using the Delft3D software package. The proposed alternative entrance modifications were based upon structural alterations of the inlet system (such as a jetty extension or submerged weir) and non-structural scenarios (such as a change of the time of the dredging campaign or the deposition location of the dredged material). It was concluded that whilst a detailed study is inevitable in order to achieve a comprehensive design plan, based upon the results of this study the construction of a submerged weir at the entrance channel can satisfy the needs of most of the stakeholders, with justifiable costs over a longer period.

A thermal impact assessment model with measured field data applied to the tidal river Weser

International Nuclear Information System (INIS)

Haeuser, J.; Eppel, D.; Mueller, A.; Nehlsen, A.; Tanzer, F.

1981-01-01

This paper presents the fundamental principles, the general outline, and a specific application of the model UTRANS (unified transport system) with emphasis on the results of application. The model simulates the temperature distribution, generated by the nuclear power plant KKU (1300 MWsub(e)), in the lower Weser river (within tidal cycle) for october 3, 1979. The model was run for a period of 24 hours. The solution area of some 15 kilometers (km 44 to km 59) consists of about 1100 discrete elements (DE) of variable size and irregular shape. (orig.) [de

Numerical analysis of stratification and destratification processes in a tidally energetic inlet with an ebb tidal delta

NARCIS (Netherlands)

Purkiani, K.; Becherer, J.; Flöser, G.; Gräwe, U.; Mohrholz, V.; Schuttelaars, H.M.; Burchard, H.

2015-01-01

Stratification and destratification processes in a tidally energetic, weakly stratified inlet in the Wadden Sea (south eastern North Sea) are investigated in this modeling study. Observations of current velocity and vertical density structure show strain-induced periodic stratification for the

The Role of Wakes in Modelling Tidal Current Turbines

Science.gov (United States)

Conley, Daniel; Roc, Thomas; Greaves, Deborah

2010-05-01

The eventual proper development of arrays of Tidal Current Turbines (TCT) will require a balance which maximizes power extraction while minimizing environmental impacts. Idealized analytical analogues and simple 2-D models are useful tools for investigating questions of a general nature but do not represent a practical tool for application to realistic cases. Some form of 3-D numerical simulations will be required for such applications and the current project is designed to develop a numerical decision-making tool for use in planning large scale TCT projects. The project is predicated on the use of an existing regional ocean modelling framework (the Regional Ocean Modelling System - ROMS) which is modified to enable the user to account for the effects of TCTs. In such a framework where mixing processes are highly parametrized, the fidelity of the quantitative results is critically dependent on the parameter values utilized. In light of the early stage of TCT development and the lack of field scale measurements, the calibration of such a model is problematic. In the absence of explicit calibration data sets, the device wake structure has been identified as an efficient feature for model calibration. This presentation will discuss efforts to design an appropriate calibration scheme which focuses on wake decay and the motivation for this approach, techniques applied, validation results from simple test cases and limitations shall be presented.

Understanding the potential risk to marine mammals from collision with tidal turbines

Energy Technology Data Exchange (ETDEWEB)

Copping, Andrea; Grear, Molly; Jepsen, Richard; Chartrand, Chris; Gorton, Alicia

2017-09-01

The advent of the marine renewable energy industry has raised questions, particularly for tidal turbines, about potential threats to populations of marine mammals. This research examines the sequence of behavioral events that lead up to a potential collision of a marine mammal with a tidal turbine, within the context of the physical environment, the attributes of the tidal device, and the biomechanical properties of a marine mammal that may resist injury from a tidal blade collision. There are currently no data available to determine the risk of collision to a marine mammal, and obtaining those data would be extremely difficult. The surrogate data examined in this research (likelihood of a marine mammal being in close proximity to a tidal turbine, biomechanics of marine mammal tissues, and engineering models) provide insight into the interaction.

Model construction of nursing service satisfaction in hospitalized tumor patients.

Science.gov (United States)

Chen, Yongyi; Liu, Jingshi; Xiao, Shuiyuan; Liu, Xiangyu; Tang, Xinhui; Zhou, Yujuan

2014-01-01

This study aims to construct a satisfaction model on nursing service in hospitalized tumor patients. Using questionnaires, data about hospitalized tumor patients' expectation, quality perception and satisfaction of hospital nursing service were obtained. A satisfaction model of nursing service in hospitalized tumor patients was established through empirical study and by structural equation method. This model was suitable for tumor specialized hospital, with reliability and validity. Patient satisfaction was significantly affected by quality perception and patient expectation. Patient satisfaction and patient loyalty was also affected by disease pressure. Hospital brand was positively correlated with patient satisfaction and patient loyalty, negatively correlated with patient complaint. Patient satisfaction was positively correlated with patient loyalty, patient complaints, and quality perception, and negatively correlated with disease pressure and patient expectation. The satisfaction model on nursing service in hospitalized tumor patients fits well. By this model, the quality of hospital nursing care may be improved.

Nurse characteristics, leadership, safety climate, emotional labour and intention to stay for nurses: a structural equation modelling approach.

Science.gov (United States)

Liang, Hui-Yu; Tang, Fu-In; Wang, Tze-Fang; Lin, Kai-Ching; Yu, Shu

2016-12-01

The aim of this study was to propose a theoretical model and apply it to examine the structural relationships among nurse characteristics, leadership characteristics, safety climate, emotional labour and intention to stay for hospital nurses. Global nursing shortages negatively affect the quality of care. The shortages can be reduced by retaining nurses. Few studies have independently examined the relationships among leadership, safety climate, emotional labour and nurses' intention to stay; more comprehensive theoretical foundations for examining nurses' intention to stay and its related factors are lacking. Cross-sectional. A purposive sample of 414 full-time nurses was recruited from two regional hospitals in Taiwan. A structured questionnaire was used to collect data from November 2013-June 2014. Structural equation modelling was employed to test the theoretical models of the relationships among the constructs. Our data supported the theoretical model. Intention to stay was positively correlated with age and the safety climate, whereas working hours per week and emotional labour were negatively correlated. The nursing position and transformational leadership indirectly affected intention to stay; this effect was mediated separately by emotional labour and the safety climate. Our data supported the model fit. Our findings provide practical implications for healthcare organizations and administrators to increase nurses' intent to stay. Strategies including a safer climate, appropriate working hours and lower emotional labour can directly increase nurses' intent to stay. Transformational leadership did not directly influence nurses' intention to stay; however, it reduced emotional labour, thereby increasing intention to stay. © 2016 John Wiley & Sons Ltd.

KIC 8164262: a heartbeat star showing tidally induced pulsations with resonant locking

Science.gov (United States)

Hambleton, K.; Fuller, J.; Thompson, S.; Prša, A.; Kurtz, D. W.; Shporer, A.; Isaacson, H.; Howard, A. W.; Endl, M.; Cochran, W.; Murphy, S. J.

2018-02-01

We present the analysis of KIC 8164262, a heartbeat star with a high-amplitude (∼1 mmag), tidally resonant pulsation (a mode in resonance with the orbit) at 229 times the orbital frequency and a plethora of tidally induced g-mode pulsations (modes excited by the orbit). The analysis combines Kepler light curves with follow-up spectroscopic data from the Keck telescope, KPNO (Kitt Peak National Observatory) 4-m Mayall telescope and the 2.7-m telescope at the McDonald observatory. We apply the binary modelling software, PHOEBE, to the Kepler light curve and radial velocity data to determine a detailed binary star model that includes the prominent pulsation and Doppler boosting, alongside the usual attributes of a binary star model (including tidal distortion and reflection). The results show that the system contains a slightly evolved F star with an M secondary companion in a highly eccentric orbit (e = 0.886). We use the results of the binary star model in a companion paper (Fuller) where we show that the prominent pulsation can be explained by a tidally excited oscillation mode held near resonance by a resonance locking mechanism.

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.

The gravitational self-interaction of the Earth's tidal bulge

Science.gov (United States)

Norsen, Travis; Dreese, Mackenzie; West, Christopher

2017-09-01

According to a standard, idealized analysis, the Moon would produce a 54 cm equilibrium tidal bulge in the Earth's oceans. This analysis omits many factors (beyond the scope of the simple idealized model) that dramatically influence the actual height and timing of the tides at different locations, but it is nevertheless an important foundation for more detailed studies. Here, we show that the standard analysis also omits another factor—the gravitational interaction of the tidal bulge with itself—which is entirely compatible with the simple, idealized equilibrium model and which produces a surprisingly non-trivial correction to the predicted size of the tidal bulge. Our analysis uses ideas and techniques that are familiar from electrostatics, and should thus be of interest to teachers and students of undergraduate E&M, Classical Mechanics (and/or other courses that cover the tides), and geophysics courses that cover the closely related topic of Earth's equatorial bulge.

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.

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.

Tidal interactions in the expanding universe - The formation of prolate systems

Science.gov (United States)

Binney, J.; Silk, J.

1979-01-01

The study estimates the magnitude of the anisotropy that can be tidally induced in neighboring initially spherical protostructures, be they protogalaxies, protoclusters, or even uncollapsed density enhancements in the large-scale structure of the universe. It is shown that the linear analysis of tidal interactions developed by Peebles (1969) predicts that the anisotropy energy of a perturbation grows to first order in a small dimensionless parameter, whereas the net angular momentum acquired is of second order. A simple model is presented for the growth of anisotropy by tidal interactions during the nonlinear stage of the development of perturbations. A possible observational test is described of the alignment predicted by the model between the orientations of large-scale perturbations and the positions of neighboring density enhancements.

Estimation of River Pollution Index in a Tidal Stream Using Kriging Analysis

Directory of Open Access Journals (Sweden)

Chiang Wei

2012-08-01

Full Text Available Tidal streams are complex watercourses that represent a transitional zone between riverine and marine systems; they occur where fresh and marine waters converge. Because tidal circulation processes cause substantial turbulence in these highly dynamic zones, tidal streams are the most productive of water bodies. Their rich biological diversity, combined with the convenience of land and water transports, provide sites for concentrated populations that evolve into large cities. Domestic wastewater is generally discharged directly into tidal streams in Taiwan, necessitating regular evaluation of the water quality of these streams. Given the complex flow dynamics of tidal streams, only a few models can effectively evaluate and identify pollution levels. This study evaluates the river pollution index (RPI in tidal streams by using kriging analysis. This is a geostatistical method for interpolating random spatial variation to estimate linear grid points in two or three dimensions. A kriging-based method is developed to evaluate RPI in tidal streams, which is typically considered as 1D in hydraulic engineering. The proposed method efficiently evaluates RPI in tidal streams with the minimum amount of water quality data. Data of the Tanshui River downstream reach available from an estuarine area validate the accuracy and reliability of the proposed method. Results of this study demonstrate that this simple yet reliable method can effectively estimate RPI in tidal streams.

A theoretical model of job retention for home health care nurses.

Science.gov (United States)

Ellenbecker, Carol Hall

2004-08-01

Predicted severe nursing shortages and an increasing demand for home health care services have made the retention of experienced, qualified nursing staff a priority for health care organizations. The purpose of this paper is to describe a theoretical model of job retention for home health care nurses. The theoretical model is an integration of the findings of empirical research related to intent to stay and retention, components of Neal's theory of home health care nursing practice and findings from earlier work to develop an instrument to measure home health care nurses' job satisfaction. The theoretical model identifies antecedents to job satisfaction of home health care nurses. The antecedents are intrinsic and extrinsic job characteristics. The model also proposes that job satisfaction is directly related to retention and indirectly related to retention though intent to stay. Individual nurse characteristics are indirectly related to retention through intent to stay. The individual characteristic of tenure is indirectly related to retention through autonomy, as an intrinsic characteristic of job satisfaction, and intent to stay. The proposed model can be used to guide research that explores gaps in knowledge about intent to stay and retention among home health care nurses.

Flow Convergence Caused by a Salinity Minimum in a Tidal Channel

Directory of Open Access Journals (Sweden)

John C. Warner

2006-12-01

Full Text Available Residence times of dissolved substances and sedimentation rates in tidal channels are affected by residual (tidally averaged circulation patterns. One influence on these circulation patterns is the longitudinal density gradient. In most estuaries the longitudinal density gradient typically maintains a constant direction. However, a junction of tidal channels can create a local reversal (change in sign of the density gradient. This can occur due to a difference in the phase of tidal currents in each channel. In San Francisco Bay, the phasing of the currents at the junction of Mare Island Strait and Carquinez Strait produces a local salinity minimum in Mare Island Strait. At the location of a local salinity minimum the longitudinal density gradient reverses direction. This paper presents four numerical models that were used to investigate the circulation caused by the salinity minimum: (1 A simple one-dimensional (1D finite difference model demonstrates that a local salinity minimum is advected into Mare Island Strait from the junction with Carquinez Strait during flood tide. (2 A three-dimensional (3D hydrodynamic finite element model is used to compute the tidally averaged circulation in a channel that contains a salinity minimum (a change in the sign of the longitudinal density gradient and compares that to a channel that contains a longitudinal density gradient in a constant direction. The tidally averaged circulation produced by the salinity minimum is characterized by converging flow at the bed and diverging flow at the surface, whereas the circulation produced by the constant direction gradient is characterized by converging flow at the bed and downstream surface currents. These velocity fields are used to drive both a particle tracking and a sediment transport model. (3 A particle tracking model demonstrates a 30 percent increase in the residence time of neutrally buoyant particles transported through the salinity minimum, as compared to

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)

Improvement of Tidal Analysis Results by a Priori Rain Fall Modelling at the Vienna and Membach stations

Science.gov (United States)

Meurers, B.; van Camp, M.; Petermans, T.

2005-12-01

We investigate how far tidal analysis results can be improved when a rain fall admittance model is applied on the superconducting gravity (SG) data. For that purpose both Vienna and Membach data have been analysed with and without a priori rain fall correction. In Membach the residual drop for most events (80%) can be explained by the rain water load, while in Vienna only 50% of all events fit the model in detail. In the other cases the Newtonian effect of vertical air mass redistribution (vertical density variation without air pressure change), predominantly connected with high vertical convection activity, e.g. thunderstorms, plays an essential role: short-term atmospheric signals show up steep gravity residual decreases of a few nms-2 within 10 - 60 min, well correlated with outdoor air temperature in most cases. However, even in those cases the water load model is able to explain the dominating part of the residual drop especially during heavy rain fall. In Vienna more than 110 events have been detected over 10 years. 84% of them are associated with heavy rain starting at or up to 10 min later than the residual drop while the rest (16%) shows no or only little rainfall. The magnitude of the gravity drop depends on the total amount of rainfall accumulated during the meteorological event. Step like signals deteriorate the frequency spectrum estimates. This even holds for tidal analysis. As the drops are of physical origin, they should not be eliminated blindly but corrected using water load modeling constrained by high temporal resolution (1 min) rain data. 3D modeling of the water mass load due to a rain event is based on the following assumptions: (1) Rain water intrudes into the uppermost soil layer (close to the topography surface) and remains there at least until rain has stopped. This is justified for a period of some hours after the rainfall as evapotranspiration is not yet effective. (2) No run-off except of sealed areas or building roofs, where water can

A cognitive learning model of clinical nursing leadership.

Science.gov (United States)

Pepin, Jacinthe; Dubois, Sylvie; Girard, Francine; Tardif, Jacques; Ha, Laurence

2011-04-01

Cognitive modeling of competencies is important to facilitate learning and evaluation. Clinical nursing leadership is considered a competency, as it is a "complex know-act" that students and nurses develop for the quality of care of patients and their families. Previous research on clinical leadership describes the attributes and characteristics of leaders and leadership, but, to our knowledge, a cognitive learning model (CLM) has yet to be developed. The purpose of our research was to develop a CLM of the clinical nursing leadership competency, from the beginning of a nursing program to expertise. An interpretative phenomenological study design was used 1) to document the experience of learning and practicing clinical leadership, and 2) to identify critical-learning turning points. Data was gathered from interviews with 32 baccalaureate students and 21 nurses from two clinical settings. An inductive analysis of data was conducted to determine the learning stages experienced: awareness of clinical leadership in nursing; integration of clinical leadership in actions; active leadership with patient/family; active leadership with the team; and, embedded clinical leadership extended to organizational level and beyond. The resulting CLM could have significant impact on both basic and continuing nursing education. Copyright © 2010 Elsevier Ltd. All rights reserved.

Hospital nurses' wellbeing at work: a theoretical model.

Science.gov (United States)

Utriainen, Kati; Ala-Mursula, Leena; Kyngäs, Helvi

2015-09-01

To develop a theoretical model of hospital nurses' wellbeing at work. The concept of wellbeing at work is presented without an exact definition and without considering different contents. A model was developed in a deductive manner and empirical data collected from nurses (n = 233) working in a university hospital. Explorative factor analysis was used. The main concepts were: patients' experience of high-quality care; assistance and support among nurses; nurses' togetherness and cooperation; fluent practical organisation of work; challenging and meaningful work; freedom to express diverse feelings in the work community; well-conducted everyday nursing; status related to the work itself; fair and supportive leadership; opportunities for professional development; fluent communication with other professionals; and being together with other nurses in an informal way. Themes included: collegial relationships; enhancing high-quality patient care; supportive and fair leadership; challenging, meaningful and well organised work; and opportunities for professional development. Object-dependent wellbeing was supported. Managers should focus on strengthening the positive aspect of wellbeing at work, focusing on providing fluently organised work practices, fair and supportive leadership and togetherness while allowing nurses to implement their own ideas and promote the experience of meaningfulness. © 2014 John Wiley & Sons Ltd.

The Historical Evolution of Theories and Conceptual Models for Nursing.

Science.gov (United States)

Hawkins, Joellen W.

The development of nursing models can be traced to the inception of nursing as a profession. Florence Nightingale laid the foundation for current nursing practice and differentiated nursing from medicine. The late 19th and early 20th centuries contributed a number of important nurse theorists, better known for other contributions to the neophyte…

Tidal current energy resource assessment in Ireland: Current status and future update

International Nuclear Information System (INIS)

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

2010-01-01

Interest in renewable energy in Ireland has increased continually over the past decade. This interest is due primarily to security of supply issues and the effects of climate change. Ireland imports over 90% of its primary energy consumption, mostly in the form of fossil fuels. The exploitation of Ireland's vast indigenous renewable energy resources is required in order to reduce this over-dependence on fossil fuel imports to meet energy demand. Various targets have been set by the Irish government to incorporate renewable energy technologies into Ireland's energy market. As a result of these targets, the development in wind energy has increased substantially over the past decade; however this method of energy extraction is intermittent and unpredictable. Ireland has an excellent tidal current energy resource and the use of this resource will assist in the development of a sustainable energy future. Energy extraction using tidal current energy technologies offers a vast and predictable energy resource. This paper reviews the currently accepted tidal current energy resource assessment for Ireland. This assessment was compiled by Sustainable Energy Ireland in a report in 2004. The assessment employed a 2-dimensional numerical model of the tidal current velocities around Ireland, and from this numerical model the theoretical tidal current energy resource was identified. With the introduction of constraints and limitations, the technical, practical, accessible and viable tidal current energy resources were obtained. The paper discusses why the assessment needs updating including the effect on the assessment of the current stage of development of tidal current turbines and their deployment technology. (author)

Facets of private practice nursing: a conceptual model.

Science.gov (United States)

Wilson, Anne; Averis, Andrea

2002-04-01

This paper critically examines the literature relating to private practice nursing. Particular attention is given to the reasons nurses choose private practice and the major issues involved. A conceptual model has been developed based on this information. Nurses' roles are expanding into different work domains. Private practice nursing is one of the advanced practice options available. It also requires the nurse to develop business knowledge and skills. A literature search was conducted of Pub-Med, Cinahl, Medline and InfoTrac databases using the terms 'private practice', 'nurse entrepreneur', 'nurses in business', Inurse practitioners', 'self-employed nurse', 'advanced practice' and 'clinical nurse specialist'. Further relevant articles were identified from the reference lists of papers detected by this literature search. In addition, conference proceedings were examined for any other material on this topic. A thorough search of the existing literature revealed one unpublished theoretically based study which examined limited aspects of private practice nursing in Victoria. A reasonable number of articles and publications that provided anecdotal and personal accounts of being a nurse in business were identified. This review highlights the need for further theoretically based research in this area of nursing, so as to expand nursing knowledge. Suggestions are given for further research in this topical area. Existing research into private practice nursing is limited and not sufficient to inform changes to policy and nurse education. More research is needed.

Nursing education in Bangladesh: a social business model.

Science.gov (United States)

Parfitt, Barbara; Nahar, Niru Shamsun

2016-06-01

The aim of this project was to develop a quality nurse education programme in Bangladesh. A sustainable social business financial model was used. The project is a collaboration between Glasgow Caledonian University and the Grameen Health Care Trust. It contributes to the UN development agenda, eradication of poverty, sustainability and the development of global partnerships. There is an acute shortage of nurses in Bangladesh but many young women who wish to become nurses are unable to do so. Women are discriminated against, have few leadership opportunities and poverty affects large proportions of rural society. The collaboration between the University and the Trust provides the necessary input to ensure a quality nursing programme. A business plan was developed, competency-based teaching introduced, infrastructure and financial management processes were set-up and an evaluation framework was put in place. The systems evaluation framework monitors the financial status of the College and the effects of the programme on students. The social business model, providing access to educational loans, has enabled 118 students to graduate into employment. The College is currently on target to be financially sustainable by 2016. This project outlines a business model that tackles poverty, gender equality and contributes to the human resource deficit. Young women are equipped as change agents and leaders. The social business model provides a mechanism for releasing funds for education to those who are impoverished. It provides a viable option for increasing the number of well-educated nurse leaders in developing countries. © 2016 International Council of Nurses.

Habitat modeling and genetic signatures of postglacial recolonization for tidal estuaries

Science.gov (United States)

Dolby, G. A.; Jacobs, D. K.

2014-12-01

Pleistocene glacial cycles are a foremost influence on the genetic diversity and species distribution patterns observed today. Though much work has centered on biotic response to such climatic forcing, little of it has regarded estuarine or other aquatic coastal taxa whose habitat formation is a function of sea level, hydrography, and coastal geomorphology. These physical parameters required for habitat formation suggest that glacial cycles impart a significant effect on such taxa through glacially driven eustatic changes. Additionally, the steepened coastline and rainfall-limited Mediterranean climate suggest limited glacial habitat for estuarine species in southern and Baja California. Here we present GIS modeled habitat for tidal estuaries for three co-distributed estuarine fishes (Gillichthys mirabilis, Quietula y-cauda, Fundulus parvipinnis) since the last glacial maximum. Parameterization of sea level and slope enables biologically relevant temporal resolution of near-millennial scale. At lowstand our approach reveals two refuges along the coast at 1000km distance from each other, with habitat rapidly increasing 15 - 12 ka during meltwater pulse 1A. Habitat area peaked in the early Holocene and began decreasing with the current stillstand roughly 7 ka, probably as a result of coastal maturation towards less tidal systems. To target the postglacial recolonization process we applied discriminant function analysis to highly polymorphic microsatellite data to partition out the alleles associated with refuges identified a priori by habitat modeling. The frequencies of these alleles were calculated for all individuals at intervening populations and regressed against geographic distance. This analysis revealed nonlinear mixing curves, suggesting uneven allelic mixing efficiency along the coastline, perhaps as a result of differential habitat origination times as indicated by the habitat models. These results highlight the dynamism of estuarine habitat in recent

Integrating Nursing Diagnostic Concepts into the Medical Entities Dictionary Using the ISO Reference Terminology Model for Nursing Diagnosis

OpenAIRE

Hwang, Jee-In; Cimino, James J.; Bakken, Suzanne

2003-01-01

Objective: The purposes of the study were (1) to evaluate the usefulness of the International Standards Organization (ISO) Reference Terminology Model for Nursing Diagnoses as a terminology model for defining nursing diagnostic concepts in the Medical Entities Dictionary (MED) and (2) to create the additional hierarchical structures required for integration of nursing diagnostic concepts into the MED.

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.)

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

MODEL DEVELOPMENT OF NURSING STUDENT LOYALTY IN POLITEKNIK OF HEALTH

Directory of Open Access Journals (Sweden)

Hammad Hammad

2017-04-01

Full Text Available Introduction: Loyalty of nursing student is an important factor that nursing education should pay attention in order to compete with other nursing educations; involved by perceived value, expectation, and quality assurance in nursing higher education. The purpose of this study was to develop a loyalty model of nursing student in nursing higher education. Methods: This study was an explanatory research with cross sectional approach. Population were nursing student in Poltekkes Banjarmasin, with 112 samples which is selected by proportional random sampling. Data was collected by giving questionnaire and analyzed by partial least square. Result: Result of this study indicates that was an effect of costumer expectation on quality assurance in nursing higher education, there was effect of costumer expectation on perceived value in nursing student, there was an effect of customer expectation on student satisfaction (4 there was effect of quality assurance in nursing higher education, there wasn’t any affect of quality assurance in nursing higher education on student satisfaction, there was effect of perceived value in nursing student on student satisfaction, there was effect of student satisfaction on student loyalty. Discussion: Overall result of this research were, student loyalty in nursing higher education developed by student satisfaction. Student satisfaction formed by perceived value. Perceived value developed from two aspects quality assurance, and student expectation, quality assurance of higher education wasn’t directly effect to student sasfaction. However, indirectly effect through student perceived value. Student satisfaction in nursing higher education was stronger effect than any other variable in this loyalty model. Loyalty model in this research can be use for improvement student loyalty on health education that focused on improvement student satisfaction without deny the other aspect. Further research is needed to analyze word of

Tidal controls on earthquake size-frequency statistics

Science.gov (United States)

Ide, S.; Yabe, S.; Tanaka, Y.

2016-12-01

The possibility that tidal stresses can trigger earthquakes is a long-standing issue in seismology. Except in some special cases, a causal relationship between seismicity and the phase of tidal stress has been rejected on the basis of studies using many small events. However, recently discovered deep tectonic tremors are highly sensitive to tidal stress levels, with the relationship being governed by a nonlinear law according to which the tremor rate increases exponentially with increasing stress; thus, slow deformation (and the probability of earthquakes) may be enhanced during periods of large tidal stress. Here, we show the influence of tidal stress on seismicity by calculating histories of tidal shear stress during the 2-week period before earthquakes. Very large earthquakes tend to occur near the time of maximum tidal stress, but this tendency is not obvious for small earthquakes. Rather, we found that tidal stress controls the earthquake size-frequency statistics; i.e., the fraction of large events increases (i.e. the b-value of the Gutenberg-Richter relation decreases) as the tidal shear stress increases. This correlation is apparent in data from the global catalog and in relatively homogeneous regional catalogues of earthquakes in Japan. The relationship is also reasonable, considering the well-known relationship between stress and the b-value. Our findings indicate that the probability of a tiny rock failure expanding to a gigantic rupture increases with increasing tidal stress levels. This finding has clear implications for probabilistic earthquake forecasting.

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.

Development of an interdisciplinary model cluster for tidal water environments

Science.gov (United States)

Dietrich, Stephan; Winterscheid, Axel; Jens, Wyrwa; Hartmut, Hein; Birte, Hein; Stefan, Vollmer; Andreas, Schöl

2013-04-01

Global climate change has a high potential to influence both the persistence and the transport pathways of water masses and its constituents in tidal waters and estuaries. These processes are linked through dispersion processes, thus directly influencing the sediment and solid suspend matter budgets, and thus the river morphology. Furthermore, the hydrologic regime has an impact on the transport of nutrients, phytoplankton, suspended matter, and temperature that determine the oxygen content within water masses, which is a major parameter describing the water quality. This project aims at the implementation of a so-called (numerical) model cluster in tidal waters, which includes the model compartments hydrodynamics, morphology and ecology. For the implementation of this cluster it is required to continue with the integration of different models that work in a wide range of spatial and temporal scales. The model cluster is thus suggested to lead to a more precise knowledge of the feedback processes between the single interdisciplinary model compartments. In addition to field measurements this model cluster will provide a complementary scientific basis required to address a spectrum of research questions concerning the integral management of estuaries within the Federal Institute of Hydrology (BfG, Germany). This will in particular include aspects like sediment and water quality management as well as adaptation strategies to climate change. The core of the model cluster will consist of the 3D-hydrodynamic model Delft3D (Roelvink and van Banning, 1994), long-term hydrodynamics in the estuaries are simulated with the Hamburg Shelf Ocean Model HAMSOM (Backhaus, 1983; Hein et al., 2012). The simulation results will be compared with the unstructured grid based SELFE model (Zhang and Bapista, 2008). The additional coupling of the BfG-developed 1D-water quality model QSim (Kirchesch and Schöl, 1999; Hein et al., 2011) with the morphological/hydrodynamic models is an

Lagoon Sediment Dynamics: A Coupled Model to Study a Medium-Term Silting of Tidal Channels

Directory of Open Access Journals (Sweden)

Marco Petti

2018-04-01

Full Text Available The silting of tidal channels is a natural process that affects several shallow lagoons and makes it difficult to navigate, requiring regular maintenance interventions. This phenomenon is the result of the complex non-linear interaction between tidal currents and wave motion. In this work, the morphodynamic evolution of the Marano and Grado lagoon is investigated by means of a two-dimensional horizontal (2DH morphological-hydrodynamic and a spectral coupled model. An innovative procedure to reproduce the overall bathymetric changes in the medium term and, in particular, the volumes deposited inside channels, is presented. An average year with a sequence of winds and tides acting over that time was reconstructed, carrying out cross correlation techniques and spectral analyses of measured data. The predicted morphological evolution matches the annual dredged volumes in the lagoon critical branches and shows the distribution of erosion and deposition of cohesive sediments according to spatially variable values of critical shear stress.

Alveolar Tidal recruitment/derecruitment and Overdistension During Four Levels of End-Expiratory Pressure with Protective Tidal Volume During Anesthesia in a Murine Lung-Healthy Model.

Science.gov (United States)

Soares, Joao Henrique Neves; Carvalho, Alysson Roncally; Bergamini, Bruno Curty; Gress, Maria Alice Kuster; Jandre, Frederico Caetano; Zin, Walter Araujo; Giannella-Neto, Antonio

2018-06-01

We compared respiratory mechanics between the positive end-expiratory pressure of minimal respiratory system elastance (PEEP minErs ) and three levels of PEEP during low-tidal-volume (6 mL/kg) ventilation in rats. Twenty-four rats were anesthetized, paralyzed, and mechanically ventilated. Airway pressure (P aw ), flow (F), and volume (V) were fitted by a linear single compartment model (LSCM) P aw (t) = E rs  × V(t) + R rs  × F(t) + PEEP or a volume- and flow-dependent SCM (VFDSCM) P aw (t) = (E 1  + E 2  × V(t)) × V(t) + (K 1  + K 2  × |F(t)|) × F(t) + PEEP, where E rs and R rs are respiratory system elastance and resistance, respectively; E 1 and E 2 × V are volume-independent and volume-dependent E rs , respectively; and K 1 and K 2  × F are flow-independent and flow-dependent R rs , respectively. Animals were ventilated for 1 h at PEEP 0 cmH 2 O (ZEEP); PEEP minErs ; 2 cmH 2 O above PEEP minErs (PEEP minErs+2 ); or 4 cmH 2 O above PEEP minErs (PEEP minErs+4 ). Alveolar tidal recruitment/derecruitment and overdistension were assessed by the index %E 2  = 100 × [(E 2  × V T )/(E 1  + |E 2 | × V T )], and alveolar stability by the slope of E rs (t). %E 2 varied between 0 and 30% at PEEP minErs in most respiratory cycles. Alveolar Tidal recruitment/derecruitment (%E 2   30) were predominant in the absence of PEEP and in PEEP levels higher than PEEP minErs , respectively. The slope of E rs (t) was different from zero in all groups besides PEEP minErs+4 . PEEP minErs presented the best compromise between alveolar tidal recruitment/derecruitment and overdistension, during 1 h of low-V T mechanical ventilation.

Tidal and subtidal exchange flows at an inlet of the Wadden Sea

Science.gov (United States)

Valle-Levinson, Arnoldo; Stanev, Emil; Badewien, Thomas H.

2018-03-01

Observations of underway velocity profiles during complete spring and neap tidal cycles were used to determine whether the spatial structures of tidal and subtidal flows at a tidal inlet in a multiple-inlet embayment are consistent with those observed at single-inlet embayments. Measurements were obtained at the Otzumer Balje, one of the multiple inlets among the East Frisian Islands of the Wadden Sea. The 1.5 km-wide inlet displayed a bathymetric profile consisting of a channel ∼15 m deep flanked by tide observations spanned 36 h in the period May 11-12, 2011, while spring tide measurements exceeded 48 h from May 17 to May 19, 2011. Analysis of observations indicate that frictional effects from bathymetry molded tidal flows. Spatial distributions of semidiurnal tidal current amplitude and phase conform to those predicted by an analytical model for a basin with one inlet. Maximum semidiurnal flows appear at the surface in the channel, furthest away from bottom friction effects. Therefore, Otzumer Balje displays tidal hydrodynamics that are independent of the other inlets of the embayment. Subtidal exchange flows are laterally sheared, with residual inflow in the channel combined with outflow over shoals. The spatial distribution of these residual flows follow theoretical expectations of tidally driven flows interacting with bathymetry. Such distribution is similar to the tidal residual circulation at other inlets with only one communication to the ocean, suggesting that at subtidal scales the Otzumer Balje responds to tidal forcing independently of the other inlets.

Tidal downscaling from the open ocean to the coast: a new approach applied to the Bay of Biscay

Science.gov (United States)

Toublanc, F.; Ayoub, N. K.; Lyard, F.; Marsaleix, P.; Allain, D. J.

2018-04-01

Downscaling physical processes from a large scale to a regional scale 3D model is a recurrent issue in coastal processes studies. The choice of boundary conditions will often greatly influence the solution within the 3D circulation model. In some regions, tides play a key role in coastal dynamics and must be accurately represented. The Bay of Biscay is one of these regions, with highly energetic tides influencing coastal circulation and river plume dynamics. In this study, three strategies are tested to force with barotropic tides a 3D circulation model with a variable horizontal resolution. The tidal forcings, as well as the tidal elevations and currents resulting from the 3D simulations, are compared to tidal harmonics extracted from satellite altimetry and tidal gauges, and tidal currents harmonics obtained from ADCP data. The results show a strong improvement of the M2 solution within the 3D model with a "tailored" tidal forcing generated on the same grid and bathymetry as the 3D configuration, compared to a global tidal atlas forcing. Tidal harmonics obtained from satellite altimetry data are particularly valuable to assess the performance of each simulation. Comparisons between sea surface height time series, a sea surface salinity database, and daily averaged 2D currents also show a better agreement with this tailored forcing.

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.

Assessment of tidal circulation and tidal current asymmetry in the Iroise sea with specific emphasis on characterization of tidal energy resources around the Ushant Island.

Science.gov (United States)

Thiébaut, Maxime; Sentchev, Alexei

2015-04-01

We use the current velocity time series recorded by High Frequency Radars (HFR) to study circulation in highly energetic tidal basin - the Iroise sea. We focus on the analysis of tidal current pattern around the Ushant Island which is a promising site of tidal energy. The analysis reveals surface current speeds reaching 4 m/s in the North of Ushant Island and in the Fromveur Strait. In these regions 1 m/s is exceeded 60% of time and up to 70% of time in center of Fromveur. This velocity value is particularly interesting because it represents the cut-in-speed of the most of marine turbine devices. Tidal current asymmetry is not always considered in tidal energy site selection. However, this quantity plays an important role in the quantification of hydrokinetic resources. Current velocity times series recorded by HFR highlights the existence of a pronounced asymmetry in current magnitude between the flood and ebb tide ranging from -0.5 to more 2.5. Power output of free-stream devices depends to velocity cubed. Thus a small current asymmetry can generate a significant power output asymmetry. Spatial distribution of asymmetry coefficient shows persistent pattern and fine scale structure which were quantified with high degree of accuracy. The particular asymmetry evolution on both side of Fromveur strait is related to the spatial distribution of the phase lag of the principal semi-diurnal tidal constituent M2 and its higher order harmonics. In Fromveur, the asymmetry is reinforced due to the high velocity magnitude of the sixth-diurnal tidal harmonics. HF radar provides surface velocity speed, however the quantification of hydrokinetic resources has to take into account the decreasing of velocity with depth. In order to highlight this phenomenon, we plot several velocity profiles given by an ADCP which was installed in the HFR study area during the same period. The mean velocity in the water column calculated by using the ADCP data show that it is about 80% of the

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

Digital Repository Service at National Institute of Oceanography (India)

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

and summer monsoon seasons of year 2000. Information on tidal signals contained in the currents were extracted using harmonic analysis - Least Squares Method and non-tidal component were analyzed using the Chi sub(o) filter. The study established...

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.

Community of inquiry model: advancing distance learning in nurse anesthesia education.

Science.gov (United States)

Pecka, Shannon L; Kotcherlakota, Suhasini; Berger, Ann M

2014-06-01

The number of distance education courses offered by nurse anesthesia programs has increased substantially. Emerging distance learning trends must be researched to ensure high-quality education for student registered nurse anesthetists. However, research to examine distance learning has been hampered by a lack of theoretical models. This article introduces the Community of Inquiry model for use in nurse anesthesia education. This model has been used for more than a decade to guide and research distance learning in higher education. A major strength of this model learning. However, it lacks applicability to the development of higher order thinking for student registered nurse anesthetists. Thus, a new derived Community of Inquiry model was designed to improve these students' higher order thinking in distance learning. The derived model integrates Bloom's revised taxonomy into the original Community of Inquiry model and provides a means to design, evaluate, and research higher order thinking in nurse anesthesia distance education courses.

Refining and validating a conceptual model of Clinical Nurse Leader integrated care delivery.

Science.gov (United States)

Bender, Miriam; Williams, Marjory; Su, Wei; Hites, Lisle

2017-02-01

To empirically validate a conceptual model of Clinical Nurse Leader integrated care delivery. There is limited evidence of frontline care delivery models that consistently achieve quality patient outcomes. Clinical Nurse Leader integrated care delivery is a promising nursing model with a growing record of success. However, theoretical clarity is necessary to generate causal evidence of effectiveness. Sequential mixed methods. A preliminary Clinical Nurse Leader practice model was refined and survey items developed to correspond with model domains, using focus groups and a Delphi process with a multi-professional expert panel. The survey was administered in 2015 to clinicians and administrators involved in Clinical Nurse Leader initiatives. Confirmatory factor analysis and structural equation modelling were used to validate the measurement and model structure. Final sample n = 518. The model incorporates 13 components organized into five conceptual domains: 'Readiness for Clinical Nurse Leader integrated care delivery'; 'Structuring Clinical Nurse Leader integrated care delivery'; 'Clinical Nurse Leader Practice: Continuous Clinical Leadership'; 'Outcomes of Clinical Nurse Leader integrated care delivery'; and 'Value'. Sample data had good fit with specified model and two-level measurement structure. All hypothesized pathways were significant, with strong coefficients suggesting good fit between theorized and observed path relationships. The validated model articulates an explanatory pathway of Clinical Nurse Leader integrated care delivery, including Clinical Nurse Leader practices that result in improved care dynamics and patient outcomes. The validated model provides a basis for testing in practice to generate evidence that can be deployed across the healthcare spectrum. © 2016 John Wiley & Sons Ltd.

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.

are predominantly mixed, semidiurnal in nature. Motion over any continental shelf is governed by the tide-driven oscillatory flow. In this paper, tidal and non-tidal characteristics of the waters of Southwest continental shelf of India are assessed using...

Tidal propagation in the Mandovi-Zuari Estuarine network, west coast of India: Impact of freshwater influx

Digital Repository Service at National Institute of Oceanography (India)

Unnikrishnan, A.S.; Shetye, S.R.; Gouveia, A.D.

the dynamics behind this behaviour, a numerical model for tidal propagation has been used that simulates the observed tidal elevations well. Momentum balance in the model is predominantly between pressure gradient and friction. In the region of undamped...

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...

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

Assessment of the Bordas-Carnot Losses within the diffuser of tidal turbines using far-field and near-field CFD models.

Science.gov (United States)

Hajaali, Arthur

2017-04-01

This project has for ambition to analyse and further the general understanding on cross-flows interactions and behaviours at the mouth of a mini/small tidal hydropower plant and a river. Although, the study of these interactions could benefit and find applications in multiple hydraulic problems, this project concentrates its focus on the influence of the transposed turbulences generated by the cross-flow into the diffuser. These eddies affect the overall performance and efficiency of the bulb-turbines by minimizing the pressure recovery. In the past, these turbulences were accounted with the implementation of the Bordas-Carnot losses coefficient for the design of tidal project using bulb-turbines. The bulb turbine technology has been the interest and subject of many scientific papers but most of them concentrate and narrow their focus on the design of the rotor, blades and combiner. This project wants to focus the design of the diffuser by performing an analysis on the development of eddies and the turbulences using computational fluid dynamic (CFD) models. The Severn estuary is endowed with one of the highest tidal range around the hemisphere. The first part of the research requires to select case studies sites such as Briton-Ferry to virtually design mini-tidal plant in 0-Dimentional (D), 2D and 3D modelling to study development and behaviour of turbulences within the diffuser. The far-field model represents the marine environment prior and after the structure where bulb turbines are located. The near-field modelling has allowed researcher to study at much higher resolution and precision the design of a single turbine feeding model with predetermined and fix boundary condition. For this reason, a near-field model is required to study in depth the behaviour and evolution of the turbulence with the diffuser. One of the main challenge and advancement of this research is to find a methodology and system to link the far-field and near-field modelling to produce an

Impact of professional nursing practice environment and psychological empowerment on nurses' work engagement: test of structural equation modelling.

Science.gov (United States)

Wang, Shanshan; Liu, Yanhui

2015-04-01

This study aimed to investigate the influence of professional nursing practice environment and psychological empowerment on nurses' work engagement. Previous researchers have acknowledged the positive influence that nurse work environment and psychological empowerment have on engagement. However, less is known about the mechanisms that explain the links between them. A predictive, non-experimental design was used to test the model in a random sample of 300 clinical nurses from two tertiary first class hospitals of Tianjin, China. The Utrecht Work Engagement Scale, the Practice Environment Scale of the Nursing Work Index and the Psychological Empowerment Scale were used to measure the study variables. Structural equation modelling revealed a good fit of the model to the data based on various fit indices (P = 0.371, χ(2) /df = 1.056, goodness of fit index = 0.967), which indicated that both professional practice environment and psychological empowerment could positively influence work engagement directly, and professional practice environment could also indirectly influence work engagement through the mediation of psychological empowerment. The study hypotheses were supported. Psychological empowerment was found to mediate the relationship between practice environments and work engagement. Administrators should provide a professional nursing practice environment and empower nurses psychologically to increase nurse engagement. © 2013 John Wiley & Sons Ltd.

Early identification of at-risk nursing students: a student support model.

Science.gov (United States)

Hopkins, T Hampton

2008-06-01

Due to the shortage of nurses in the health care industry, colleges offering associate-degree nursing programs are beginning to pay more attention to attrition and the factors contributing to success. Alogistic regression model was used to explain the cognitive and noncognitive variables that contribute to success in a nursing fundamentals course. Although much work is necessary to fully understand first-semester nursing students' retention and success, an early identification model is explored to better support students as they enter associate-degree nursing programs.

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)

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.

Determining the Effect of the Lunar Nodal Cycle on Tidal Mixing and North Pacific Climate Variability

Science.gov (United States)

Ullman, D. J.; Schmittner, A.; Danabasoglu, G.; Norton, N. J.; Müller, M.

2016-02-01

Oscillations in the moon's orbit around the earth modulate regional tidal dissipation with a periodicity of 18.6 years. In regions where the diurnal tidal constituents dominate diapycnal mixing, this Lunar Nodal Cycle (LNC) may be significant enough to influence ocean circulation, sea surface temperature, and climate variability. Such periodicity in the LNC as an external forcing may provide a mechanistic source for Pacific decadal variability (i.e. Pacific Decadal Oscillation, PDO) where diurnal tidal constituents are strong. We have introduced three enhancements to the latest version of the Community Earth System Model (CESM) to better simulate tidal-forced mixing. First, we have produced a sub-grid scale bathymetry scheme that better resolves the vertical distribution of the barotropic energy flux in regions where the native CESM grid does not resolve high spatial-scale bathymetric features. Second, we test a number of alternative barotropic tidal constituent energy flux fields that are derived from various satellite altimeter observations and tidal models. Third, we introduce modulations of the individual diurnal and semi-diurnal tidal constituents, ranging from monthly to decadal periods, as derived from the full lunisolar tidal potential. Using both ocean-only and fully-coupled configurations, we test the influence of these enhancements, particularly the LNC modulations, on ocean mixing and bidecadal climate variability in CESM.

Development of a nursing practice based competency model for the Flemish master of nursing and obstetrics degree.

Science.gov (United States)

De Clercq, Gerlinde; Goelen, Guido; Danschutter, Dirk; Vermeulen, Joeri; Huyghens, Luc

2011-01-01

The aim was to identify a set of competences for the Flemish academic Master of Nursing and Obstetrics degree that answer perceived needs in health care. The competency model was to demonstrate a degree of consensus among key nurses. The study was conducted in all Flemish hospitals registered to have 400 beds or more. Head nurses of surgery, geriatrics and intensive care units were eligible to participate, as well as one nurse from administration per hospital. A two round Delphi process allowed participants to comment on items identified in an analysis of existing international competency profiles of master level nurses and adapted to the Flemish context. Competences agreed to by 90% of the respondents were considered to have consensus. Fifteen out of 19 eligible hospitals were recruited in the study, 45 nurses participated in the Delphi panel. Consensus was reached on 31 competences that can be assigned to 5 nurse's roles: nursing expert, innovator, researcher, educator and manager. The resulting competency profile is in accordance with published profiles for similar programs. The reported study demonstrates a practical method to develop a consensus competency model for an academic master program based on the input of key individuals in mainstream nursing. 2010 Elsevier Ltd. All rights reserved.

Effect of mentoring on professional values in model C clinical nurse leader graduates.

Science.gov (United States)

Gazaway, Shena B; Anderson, Lori; Schumacher, Autumn; Alichnie, Chris

2018-04-19

Nursing graduates acquire their nursing values by professional socialization. Mentoring is a crucial support mechanism for these novice nurses, yet little is known about the model C clinical nurse leader graduate and the effects of mentoring. This investigation examined how mentoring affected the development of professional nursing values in the model C clinical nurse leader graduate. A longitudinal design was used to survey model C clinical nurse leader graduates before and after graduation to determine how different types of mentoring relationships influenced professional values. Demographic surveys documented participant characteristics and the Nurses Professional Values Scale - Revised (NPVS-R) assessed professional nursing values. Mean NPVS-R scores increased after graduation for the formally mentored participants, while the NPVS-R scores decreased or remained unchanged for the other mentoring groups. However, no significant difference was found in NPVS-R scores over time (p = .092) or an interaction between the NPVS-R scores and type of mentoring relationships (p = .09). These results suggest that model C clinical nurse leader graduate participants experiencing formal mentoring may develop professional nursing values more than their colleagues. Formal mentoring relationships are powerful and should be used to promote professional values for model C clinical nurse leader graduates. © 2018 John Wiley & Sons Ltd.

Tidal deformations of spinning black holes in Bowen–York initial data

International Nuclear Information System (INIS)

Cabero, Miriam; Krishnan, Badri

2015-01-01

We study the tidal deformations of the shape of a spinning black hole horizon due to a binary companion in the Bowen–York initial data set. We use the framework of quasi-local horizons and identify a black hole by marginally outer trapped surfaces. The intrinsic horizon geometry is specified by a set of mass and angular-momentum multipole moments M n and J n , respectively. The tidal deformations are described by the change in these multipole moments caused by an external perturbation. This leads us to define two sets of dimensionless numbers, the tidal coefficients for M n and J n , which specify the deformations of a black hole with a binary companion. We compute these tidal coefficients in a specific model problem, namely the Bowen–York initial data set for binary black holes. We restrict ourselves to axisymmetric situations and to small spins. Within this approximation, we analytically compute the conformal factor, the location of the marginally trapped surfaces, and finally the multipole moments and the tidal coefficients. (paper)

Nurse Practitioner-Physician Comanagement: A Theoretical Model to Alleviate Primary Care Strain.

Science.gov (United States)

Norful, Allison A; de Jacq, Krystyna; Carlino, Richard; Poghosyan, Lusine

2018-05-01

Various models of care delivery have been investigated to meet the increasing demands in primary care. One proposed model is comanagement of patients by more than 1 primary care clinician. Comanagement has been investigated in acute care with surgical teams and in outpatient settings with primary care physicians and specialists. Because nurse practitioners are increasingly managing patient care as independent clinicians, our study objective was to propose a model of nurse practitioner-physician comanagement. We conducted a literature search using the following key words: comanagement; primary care; nurse practitioner OR advanced practice nurse. From 156 studies, we extracted information about nurse practitioner-physician comanagement antecedents, attributes, and consequences. A systematic review of the findings helped determine effects of nurse practitioner-physician comanagement on patient care. Then, we performed 26 interviews with nurse practitioners and physicians to obtain their perspectives on nurse practitioner-physician comanagement. Results were compiled to create our conceptual nurse practitioner-physician comanagement model. Our model of nurse practitioner-physician comanagement has 3 elements: effective communication; mutual respect and trust; and clinical alignment/shared philosophy of care. Interviews indicated that successful comanagement can alleviate individual workload, prevent burnout, improve patient care quality, and lead to increased patient access to care. Legal and organizational barriers, however, inhibit the ability of nurse practitioners to practice autonomously or with equal care management resources as primary care physicians. Future research should focus on developing instruments to measure and further assess nurse practitioner-physician comanagement in the primary care practice setting. © 2018 Annals of Family Medicine, Inc.

Modelling Digital Knowledge Transfer: Nurse Supervisors Transforming Learning at Point of Care to Advance Nursing Practice

Directory of Open Access Journals (Sweden)

Carey Mather

2017-05-01

Full Text Available Limited adoption of mobile technology for informal learning and continuing professional development within Australian healthcare environments has been explained primarily as an issue of insufficient digital and ehealth literacy of healthcare professionals. This study explores nurse supervisors’ use of mobile technology for informal learning and continuing professional development both for their own professional practice, and in their role in modelling digital knowledge transfer, by facilitating the learning and teaching of nursing students in the workplace. A convenience sample of 27 nurse supervisors involved with guiding and supporting undergraduate nurses participated in one of six focus groups held in two states of Australia. Expanding knowledge emerged as the key theme of importance to this group of clinicians. Although nurse supervisors regularly browsed Internet sources for learning and teaching purposes, a mixed understanding of the mobile learning activities that could be included as informal learning or part of formal continuing professional development was detected. Participants need educational preparation and access to mobile learning opportunities to improve and maintain their digital and ehealth literacy to appropriately model digital professionalism with students. Implementation of mobile learning at point of care to enable digital knowledge transfer, augment informal learning for students and patients, and support continuing professional development opportunities is necessary. Embedding digital and ehealth literacy within nursing curricula will promote mobile learning as a legitimate nursing function and advance nursing practice.

Tidal sails : an alternative to turbines for harvesting tidal current energy

Energy Technology Data Exchange (ETDEWEB)

Hanssen, J.E. [Tidal Sails, Haugesund (Norway)

2008-07-01

Tidal sail technology harnesses the energy of tidal streams in order to produce electricity. Tidal currents move the sails that are attached to wires that rotate generator wheels to produce electricity. The technology has a low impact on the surrounding environment and is simple to install. This presentation discussed the methods used to determine the influence of relative sail velocity and measure estimated energy output levels. The sails were recently tested at an on-grid tidal stream pilot in the Norwegian Arctic. A 300 kW turbine installed at the site demonstrated that the site was suitable for a full-scale development of 20 tripod-mounted 600 kW turbines placed at 50 m depth. It was estimated that the 10 strings of 1000 m length provided between 200 and 250 GWh per year. The sails have also been used at a high speed site in Washington state in the United States. The 25 m pilot plant was installed to verify site suitability and examine sail behaviour in real, high-flow currents. It is expected that the technology will be fully commercialized by 2011. Other pilot tests are being conducted to examine flow behaviour; mooring and flotation functionality; and launch and lift capabilities. Engineering work is ongoing to examine plant designs, variable sail spacing, and collaborations with key component suppliers. tabs., figs.

A system shift in tidal choking due to the construction of Yangshan Harbour, Shanghai, China

Science.gov (United States)

Guo, Wenyun; Wang, Xiao Hua; Ding, Pingxing; Ge, Jianzhong; Song, Dehai

2018-06-01

Tidal choking is a geometric feature caused by a narrowed channel. Construction of the Yangshan Harbour, Shanghai, China obstructed three key channels and intensively changed the local geometry and topography. In this study nine numerical experiments based on the Finite-Volume Community Ocean Model are conducted to study the project's influence on tidal characteristics. Results show that stronger tidal choking happened at the East Entrance after project, mainly due to the jet induced water-level drop forced by Bernoulli law and the longer and narrower geometry. The stronger tidal choking forces a faster flow and larger tidal energy flux at the choked channel while reducing the tidal amplitude in the Inner Harbour Area (IHA). The scouring on this channel reduces the choking effect but further enlarges tidal energy flux. Moreover, damming the channels decrease the tidal amplitude at the lee side of tidal propagating direction while increasing the amplitude on the stoss side. The dams also decrease the tidal current on both sides, and meanwhile develop two patches with stronger current aside the dam. The project induced changes in tidal characteristics are complex in space, and perturbations in bathymetry increase this complexity. Yangshan Harbour's construction induces little changes in the total tidal energy density in the IHA, but induces obvious changes in the spatial distribution of tidal energy. Although this study is site-specific, the findings may be applicable to tidal dynamics in land reclamation close to open seas, such as the dramatic reclamation of islands in the South China Sea.

Preliminary clinical nursing leadership competency model: a qualitative study from Thailand.

Science.gov (United States)

Supamanee, Treeyaphan; Krairiksh, Marisa; Singhakhumfu, Laddawan; Turale, Sue

2011-12-01

This qualitative study explored the clinical nursing leadership competency perspectives of Thai nurses working in a university hospital. To collect data, in-depth interviews were undertaken with 23 nurse administrators, and focus groups were used with 31 registered nurses. Data were analyzed using content analysis, and theory development was guided by the Iceberg model. Nurses' clinical leadership competencies emerged, comprising hidden characteristics and surface characteristics. The hidden characteristics composed three elements: motive (respect from the nursing and healthcare team and being secure in life), self-concept (representing positive attitudes and values), and traits (personal qualities necessary for leadership). The surface characteristics comprised specific knowledge of nurse leaders about clinical leadership, management and nursing informatics, and clinical skills, such as coordination, effective communication, problem solving, and clinical decision-making. The study findings help nursing to gain greater knowledge of the essence of clinical nursing leadership competencies, a matter critical for theory development in leadership. This study's results later led to the instigation of a training program for registered nurse leaders at the study site, and the formation of a preliminary clinical nursing leadership competency model. © 2011 Blackwell Publishing Asia Pty Ltd.

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.

An Introduction to the Partial Credit Model for Developing Nursing Assessments.

Science.gov (United States)

Fox, Christine

1999-01-01

Demonstrates how the partial credit model, a variation of the Rasch Measurement Model, can be used to develop performance-based assessments for nursing education. Applies the model using the Practical Knowledge Inventory for Nurses. (SK)

Stirring up a storm: convective climate variability on tidally locked exoplanets

Science.gov (United States)

Koll, D. D. B.; Cronin, T.

2017-12-01

Earth-sized exoplanets are extremely common in the galaxy and many of them are likely tidally locked, such that they have permanent day- and nightsides. Astronomers have started to probe the atmospheres of such planets, which raises the question: can tidally locked planets support habitable climates and life?Several studies have explored this question using global circulation models (GCMs). Not only did these studies find that tidally locked Earth analogs can indeed sustain habitable climates, their large day-night contrast should also create a distinct cloud structure that could help astronomers identify such planets. These studies, however, relied on GCMs which do not explicitly resolve convection, raising the question of how robust their results are.Here we consider the dynamics of clouds and convection on a tidally locked planet using the System for Atmospheric Modeling (SAM) cloud-resolving model. We simulate a 3d `channel', representing an equatorial strip that covers both day- and nightside of a tidally locked planet. We use interactive radiation and an interactive slab ocean surface and investigate the response to changes in the stellar constant. We find mean climates that are broadly comparable to those produced by a GCM. However, when the slab ocean is shallow, we also find internal variability that is far bigger than in a GCM. Convection in a tidally locked domain can self-organize in a dramatic fashion, with large outbursts of convection followed by periods of relative calm. We show that one of the timescales for this behavior is set by the time it takes for a dry gravity wave to travel between day- and nightside. The quasi-periodic self-organization of clouds can vary the planetary albedo by up to 50%. Changes this large are potentially detectable with future space telescopes, which raises the prospect of using convectively driven variability to identify high priority targets in the search for life around other stars.

Tidal Friction in the Earth-Moon System and Laplace Planes: Darwin Redux

Science.gov (United States)

Rubincam, David P.

2015-01-01

The dynamical evolution of the Earth-Moon system due to tidal friction is treated here. George H. Darwin used Laplace planes (also called proper planes) in his study of tidal evolution. The Laplace plane approach is adapted here to the formalisms of W.M. Kaula and P. Goldreich. Like Darwin, the approach assumes a three-body problem: Earth, Moon, and Sun, where the Moon and Sun are point-masses. The tidal potential is written in terms of the Laplace plane angles. The resulting secular equations of motion can be easily integrated numerically assuming the Moon is in a circular orbit about the Earth and the Earth is in a circular orbit about the Sun. For Earth-Moon distances greater than 10 Earth radii, the Earth's approximate tidal response can be characterized with a single parameter, which is a ratio: a Love number times the sine of a lag angle divided by another such product. For low parameter values it can be shown that Darwin's low-viscosity molten Earth, M. Ross's and G. Schubert's model of an Earth near melting, and Goldreich's equal tidal lag angles must all give similar histories. For higher parameter values, as perhaps has been the case at times with the ocean tides, the Earth's obliquity may have decreased slightly instead of increased once the Moon's orbit evolved further than 50 Earth radii from the Earth, with possible implications for climate. This is contrast to the other tidal friction models mentioned, which have the obliquity always increasing with time. As for the Moon, its orbit is presently tilted to its Laplace plane by 5.2deg. The equations do not allow the Moon to evolve out of its Laplace plane by tidal friction alone, so that if it was originally in its Laplace plane, the tilt arose with the addition of other mechanisms, such as resonance passages.

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.

Maximizing the nurses' preferences in nurse scheduling problem: mathematical modeling and a meta-heuristic algorithm

Science.gov (United States)

Jafari, Hamed; Salmasi, Nasser

2015-09-01

The nurse scheduling problem (NSP) has received a great amount of attention in recent years. In the NSP, the goal is to assign shifts to the nurses in order to satisfy the hospital's demand during the planning horizon by considering different objective functions. In this research, we focus on maximizing the nurses' preferences for working shifts and weekends off by considering several important factors such as hospital's policies, labor laws, governmental regulations, and the status of nurses at the end of the previous planning horizon in one of the largest hospitals in Iran i.e., Milad Hospital. Due to the shortage of available nurses, at first, the minimum total number of required nurses is determined. Then, a mathematical programming model is proposed to solve the problem optimally. Since the proposed research problem is NP-hard, a meta-heuristic algorithm based on simulated annealing (SA) is applied to heuristically solve the problem in a reasonable time. An initial feasible solution generator and several novel neighborhood structures are applied to enhance performance of the SA algorithm. Inspired from our observations in Milad hospital, random test problems are generated to evaluate the performance of the SA algorithm. The results of computational experiments indicate that the applied SA algorithm provides solutions with average percentage gap of 5.49 % compared to the upper bounds obtained from the mathematical model. Moreover, the applied SA algorithm provides significantly better solutions in a reasonable time than the schedules provided by the head nurses.

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

Science.gov (United States)

Gong, Wenping; Schuttelaars, Henk; Zhang, Heng

2016-05-01

Different types of tidal asymmetry (see review of de Swart and Zimmerman Annu Rev Fluid Mech 41: 203-229, 2009) are examined in this study. We distinguish three types of tidal asymmetry: duration and magnitude differences between flood and ebb tidal flow, duration difference between the rising and falling tides. For waterborne substance transport, the first two asymmetries are important while the last one is not. In this study, we take the Huangmaohai Estuary (HE), Pearl River Delta, China as an example to examine the spatio-temporal variations of the tidal asymmetry in a mixed semidiurnal tidal regime and to explain them by investigating the associated mechanisms. The methodology defining the tidal duration asymmetry and velocity skewness, proposed by Nidzieko (J Geophys Res 115: C08006. doi: 10.1029/2009JC005864 , 2010) and synthesized by Song et al. (J Geophys Res 116: C12007. doi: 10.1029/2011JC007270 , 2011), is utilized here and referred to as tidal duration asymmetry (TDA) and flow velocity asymmetry (FVA), respectively. The methodology is further used to quantify the flow duration asymmetry (FDA). A positive asymmetry means a shorter duration of low water slack for FDA, a shorter duration of the rising tide for TDA, and a flood dominance for FVA and vice versa. The Regional Ocean Modeling System (ROMS) model is used to provide relatively long-term water elevation and velocity data and to conduct diagnostic experiments. In the HE, the main tidal constituents are diurnal tides K 1, O 1 and semidiurnal tides M 2 and S 2. The interaction among the diurnal and semidiurnal tides generates a negative tidal asymmetry, while the interactions among semidiurnal tides and their overtides or compound tides result in a positive tidal asymmetry. The competition among the above interactions determines the FDA and TDA, whereas for the FVA, aside from the interaction among different tidal constituents, an extra component, the residual flow, plays an important role. The

Gamma-Ray Bursts from tidally spun-up Wolf-Rayet stars?

OpenAIRE

Detmers, R. G.; Langer, N.; Podsiadlowski, Ph.; Izzard, R. G.

2008-01-01

Context. The collapsar model requires rapidly rotating Wolf-Rayet stars as progenitors of long gamma-ray bursts. However, Galactic Wolf-Rayet stars rapidly lose angular momentum due to their intense stellar winds. Aims. We investigate whether the tidal interaction of a Wolf-Rayet star with a compact object in a binary system can spin up the Wolf-Rayet star enough to produce a collapsar. Methods. We compute the evolution of close Wolf-Rayet binaries, including tidal angular momentum exchange, ...

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

Reconciling professional identity: A grounded theory of nurse academics' role modelling for undergraduate students.

Science.gov (United States)

Baldwin, A; Mills, J; Birks, M; Budden, L

2017-12-01

Role modelling by experienced nurses, including nurse academics, is a key factor in the process of preparing undergraduate nursing students for practice, and may contribute to longevity in the workforce. A grounded theory study was undertaken to investigate the phenomenon of nurse academics' role modelling for undergraduate students. The study sought to answer the research question: how do nurse academics role model positive professional behaviours for undergraduate students? The aims of this study were to: theorise a process of nurse academic role modelling for undergraduate students; describe the elements that support positive role modelling by nurse academics; and explain the factors that influence the implementation of academic role modelling. The study sample included five second year nursing students and sixteen nurse academics from Australia and the United Kingdom. Data was collected from observation, focus groups and individual interviews. This study found that in order for nurse academics to role model professional behaviours for nursing students, they must reconcile their own professional identity. This paper introduces the theory of reconciling professional identity and discusses the three categories that comprise the theory, creating a context for learning, creating a context for authentic rehearsal and mirroring identity. Copyright © 2017 Elsevier Ltd. All rights reserved.

FORWARD AND INVERSE MODELING OF THE EMISSION AND TRANSMISSION SPECTRUM OF GJ 436B: INVESTIGATING METAL ENRICHMENT, TIDAL HEATING, AND CLOUDS

Energy Technology Data Exchange (ETDEWEB)

Morley, Caroline V. [Department of Astronomy, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States); Knutson, Heather [Division of Geological and Planetary Sciences, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Line, Michael [School of Earth and Space Exploration, Arizona State University, 781 South Terrace Road, Tempe, AZ 85281 (United States); Fortney, Jonathan J.; Teal, Dillon [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Thorngren, Daniel [Department of Physics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Marley, Mark S.; Lupu, Roxana, E-mail: caroline.morley@cfa.harvard.edu [NASA Ames Research Center, Moffett Field, CA 94035 (United States)

2017-02-01

The Neptune-mass GJ 436b is one of the most studied transiting exoplanets with repeated measurements of its thermal emission and transmission spectra. We build on previous studies to answer outstanding questions about this planet, including its potentially high metallicity and tidal heating of its interior. We present new observations of GJ 436b’s thermal emission at 3.6 and 4.5 μ m, which reduce uncertainties in estimates of GJ 436b’s flux at those wavelengths and demonstrate consistency between Spitzer observations spanning more than 7 yr. We analyze the Spitzer thermal emission photometry and Hubble WFC3 transmission spectrum. We use a dual-pronged modeling approach of both self-consistent and retrieval models. We vary the metallicity, intrinsic luminosity from tidal heating, disequilibrium chemistry, and heat redistribution. We also study clouds and photochemical hazes, but do not find strong evidence for either. The self-consistent and retrieval models combine to suggest that GJ 436b has a high atmospheric metallicity, with best fits at or above several hundred times solar metallicity, tidal heating warming its interior with best-fit intrinsic effective temperatures around 300–350 K, and disequilibrium chemistry. High metal enrichments (>600× solar) occur from the accretion of rocky, rather than icy, material. Assuming the interior temperature T {sub int} ∼ 300–350 K, we find a dissipation factor Q ′ ∼ 2 × 10{sup 5}–10{sup 6}, larger than Neptune’s Q ′, implying a long tidal circularization timescale for the orbit. We suggest that Neptune-mass planets may be more diverse than imagined, with metal enhancements spanning several orders of magnitude, to perhaps over 1000× solar metallicity. High-fidelity observations with instruments like the James Webb Space Telescope will be critical for characterizing this diversity.

Feasibility of tidal power development in the Bay of Fundy

Energy Technology Data Exchange (ETDEWEB)

1969-01-01

A committee was formed to carry out technical studies on the feasibility of a tidal power plant in the Bay of Fundy. Basic information was collected on the physical, geological, climatic, and tidal characteristics of the area to determine areas for more intense investigation. Studies were conducted on the possible effects of the plant on navigation, ground transportation, fisheries, and area development. Electric power marketing and transmission were also examined, as well as the basic concepts for extracting tidal energy. A number of potential sites were examined, and the three most promising sites were selected for preliminary design and cost estimates. Computerized models were used at appropriate stages in order to evaluate various tidal power schemes. This report presents a summary of the committee's investigations. It was seen that a site at the entrance to Cobequid Bay would have an economic advantage over the other sites considered. From the results of the design studies, it was concluded that a long period of construction, plus extensive capital investment, would be required. However, the lowest unit cost of output was calculated at 5.6 mills/kWh, substantially above the incremental cost of energy available from existing sources. Under current economic conditions, the tidal power plant would not be feasible. 4 figs., 1 tab.

Summertime influences of tidal energy advection on the surface energy balance in a mangrove forest

Directory of Open Access Journals (Sweden)

J. G. Barr

2013-01-01

Full Text Available Mangrove forests are ecosystems susceptible to changing water levels and temperatures due to climate change as well as perturbations resulting from tropical storms. Numerical models can be used to project mangrove forest responses to regional and global environmental changes, and the reliability of these models depends on surface energy balance closure. However, for tidal ecosystems, the surface energy balance is complex because the energy transport associated with tidal activity remains poorly understood. This study aimed to quantify impacts of tidal flows on energy dynamics within a mangrove ecosystem. To address the research objective, an intensive 10-day study was conducted in a mangrove forest located along the Shark River in the Everglades National Park, FL, USA. Forest–atmosphere turbulent exchanges of energy were quantified with an eddy covariance system installed on a 30-m-tall flux tower. Energy transport associated with tidal activity was calculated based on a coupled mass and energy balance approach. The mass balance included tidal flows and accumulation of water on the forest floor. The energy balance included temporal changes in enthalpy, resulting from tidal flows and temperature changes in the water column. By serving as a net sink or a source of available energy, flood waters reduced the impact of high radiational loads on the mangrove forest. Also, the regression slope of available energy versus sink terms increased from 0.730 to 0.754 and from 0.798 to 0.857, including total enthalpy change in the water column in the surface energy balance for 30-min periods and daily daytime sums, respectively. Results indicated that tidal inundation provides an important mechanism for heat removal and that tidal exchange should be considered in surface energy budgets of coastal ecosystems. Results also demonstrated the importance of including tidal energy advection in mangrove biophysical models that are used for predicting ecosystem

Growing up and role modeling: a theory in Iranian nursing students' education.

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Mokhtari Nouri, Jamileh; Ebadi, Abbas; Alhani, Fatemeh; Rejeh, Nahid

2014-11-16

One of the key strategies in students' learning is being affected by models. Understanding the role-modeling process in education will help to make greater use of this training strategy. The aim of this grounded theory study was to explore Iranian nursing students and instructors' experiences about role modeling process. Data was analyzed by Glaserian's Grounded Theory methodology through semi-structured interviews with 7 faculty members, 2 nursing students; the three focus group discussions with 20 nursing students based on purposive and theoretical sampling was done for explaining role modeling process from four nursing faculties in Tehran. Through basic coding, an effort to comprehensive growth and excellence was made with the basic social process consisting the core category and through selective coding three phases were identified as: realizing and exposure to inadequate human and professional growth, facilitating human and professional growth and evolution. The role modeling process is taking place unconscious, involuntary, dynamic and with positive progressive process in order to facilitate overall growth in nursing student. Accordingly, the design and implementation of the designed model can be used to make this unconscious to conscious, active and voluntarily processes a process to help education administrators of nursing colleges and supra organization to prevent threats to human and professional in nursing students' education and promote nursing students' growth.

Numerical modeling of persian gulf salinity variations due to tidal effects

International Nuclear Information System (INIS)

Sabbagh Yazdi, S.R.

2004-01-01

Numerical modeling of salinity changes in marine environment of Persian Gulf is investigated in this paper. Computer simulation of the problem is performed by the solution of a convection-diffusion equation for salinity concentration coupled with the hydrodynamic equations. The hydrodynamic equations consist of shallow water equations of continuity and motion in horizontal plane. The effects of rain and evaporations are considered in the continuity equation and the effects of bed slope and friction, as well as Coriolis effects are considered in two equations of motion. The cell vertex finite volume method is applied for solving the governing equations on triangular unstructured meshes. Using unstructured meshes provides great flexibility for modeling the flow problems in arbitrary and complex geo metrics, such as Persia Gulf domain. The results of evaporation and Coriolis effects, as well as imposing river and tidal boundary conditions to the hydrodynamic model of Persian Gulf (considering variable topology rough bed) are compared with predictions of Admiralty Tide Table, Which are obtained from the harmonic analysis. The performance of the developed computer model is demonstrated by simulation of salinity changes due to inflow effects and diffusion effects as well as computed currents

Causal modeling of self-concept, job satisfaction, and retention of nurses.

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Cowin, Leanne S; Johnson, Maree; Craven, Rhonda G; Marsh, Herbert W

2008-10-01

The critical shortage of nurses experienced throughout the western world has prompted researchers to examine one major component of this complex problem - the impact of nurses' professional identity and job satisfaction on retention. A descriptive correlational design with a longitudinal element was used to examine a causal model of nurses' self-concept, job satisfaction, and retention plans in 2002. A random sample of 2000 registered nurses was selected from the state registering authority listing. A postal survey assessing multiple dimensions of nurses' self-concept (measured by the nurse self-concept questionnaire), job satisfaction (measured by the index of work satisfaction) was undertaken at Time 1 (n=528) and 8 months later at Time 2 (n=332) (including retention plans (measured by the Nurse Retention Index). Using confirmatory factor analysis, correlation matrices and path analysis, measurement and structural models were examined on matching pairs of data from T1 and T2 (total sample N=332). Nurses' self-concept was found to have a stronger association with nurses' retention plans (B=.45) than job satisfaction (B=.28). Aspects of pay and task were not significantly related to retention plans, however, professional status (r=.51), and to a lesser extent, organizational policies (r=.27) were significant factors. Nurses' general self-concept was strongly related (r=.57) to retention plans. Strategies or interventions requiring implementation and evaluation include: counseling to improve nurse general self-concept, education programs and competencies in health communication between health professionals, reporting of nurse-initiated programs with substantial patient benefit, nurse-friendly organizational policies, common health team learning opportunities, and autonomous practice models.

Development of an International School Nurse Asthma Care Coordination Model.

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Garwick, Ann W; Svavarsdóttir, Erla Kolbrun; Seppelt, Ann M; Looman, Wendy S; Anderson, Lori S; Örlygsdóttir, Brynja

2015-03-01

To identify and compare how school nurses in Reykjavik, Iceland and St. Paul, Minnesota coordinated care for youth with asthma (ages 10-18) and to develop an asthma school nurse care coordination model. Little is known about how school nurses coordinate care for youth with asthma in different countries. A qualitative descriptive study design using focus group data. Six focus groups with 32 school nurses were conducted in Reykjavik (n = 17) and St. Paul (n = 15) using the same protocol between September 2008 and January 2009. Descriptive content analytic and constant comparison strategies were used to categorize and compare how school nurses coordinated care, which resulted in the development of an International School Nurse Asthma Care Coordination Model. Participants in both countries spontaneously described a similar asthma care coordination process that involved information gathering, assessing risk for asthma episodes, prioritizing healthcare needs and anticipating and planning for student needs at the individual and school levels. This process informed how they individualized symptom management, case management and/or asthma education. School nurses played a pivotal part in collaborating with families, school and healthcare professionals to ensure quality care for youth with asthma. Results indicate a high level of complexity in school nurses' approaches to asthma care coordination that were responsive to the diverse and changing needs of students in school settings. The conceptual model derived provides a framework for investigators to use in examining the asthma care coordination process of school nurses in other geographic locations. © 2014 John Wiley & Sons Ltd.

Spectral responses of gravel beaches to tidal signals

Science.gov (United States)

Geng, Xiaolong; Boufadel, Michel C.

2017-01-01

Tides have been recognized as a major driving forcing affecting coastal aquifer system, and deterministic modeling has been very effective in elucidating mechanisms caused by tides. However, such modeling does not lend itself to capture embedded information in the signal, and rather focuses on the primary processes. Here, using yearlong data sets measured at beaches in Alaska Prince William Sound, we performed spectral and correlation analyses to identify temporal behavior of pore-water pressure, temperature and salinity. We found that the response of the beach system was characterized by fluctuations of embedded diurnal, semidiurnal, terdiurnal and quarterdiurnal tidal components. Hydrodynamic dispersion of salinity and temperature, and the thermal conductivity greatly affected pore water signals. Spectral analyses revealed a faster dissipation of the semi-diurnal component with respect to the diurnal components. Correlation functions showed that salinity had a relatively short memory of the tidal signal when inland freshwater recharge was large. In contrast, the signature of the tidal signal on pore-water temperature persisted for longer times, up to a week. We also found that heterogeneity greatly affected beach response. The response varied from a simple linear mapping in the frequency domain to complete modulation and masking of the input frequencies.

The value of delay in tidal energy development

International Nuclear Information System (INIS)

MacDougall, Shelley L.

2015-01-01

Despite robust research, prototype development and demonstration of in-stream tidal energy devices, progress to the commercialization stage has been slow. Some of this can be attributed to a lack readiness or financing. However, when uncertainty is high, a developer may choose to delay a project until more is known. The option to delay has value for a company. This study applies the real option valuation model to an investment in a 10 MW array of in-stream tidal energy conversion devices at the Fundy Ocean Research Centre for Energy (FORCE) in the Bay of Fundy, Nova Scotia, Canada. The values of investing and the option to delay are calculated. A sensitivity analysis of key drivers and scenarios with various input values to the option model are constructed to observe the impact on the 'invest versus delay' decision. The analysis suggests there is value in owning the option to develop, by leasing a FORCE berth, but waiting while uncertainty is resolved. Implications for policy-setting are discussed. - Highlights: • Analyze an invest-vs-delay decision in tidal energy conversion using real options. • Assess whether conditions are conducive to an economically rational decision to delay. • Identify aspects of the decision that can be influenced by government policy.

Gordon's model applied to nursing care of people with depression.

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Temel, M; Kutlu, F Y

2015-12-01

Psychiatric nurses should consider the patient's biological, psychological and social aspects. Marjory Gordon's Functional Health Pattern Model ensures a holistic approach for the patient. To examine the effectiveness of Gordon's Functional Health Pattern Model in reducing depressive symptoms, increasing self-efficacy, coping with depression and increasing hope in people with depression. A quasi-experimental two-group pre-test and post-test design was adopted. Data were collected from April 2013 to May 2014 from people with depression at the psychiatry clinic of a state hospital in Turkey; they were assigned to the intervention (n = 34) or control group (n = 34). The intervention group received nursing care according to Gordon's Functional Health Pattern Model and routine care, while the control group received routine care only. The Beck Depression Inventory, Beck Hopelessness Scale and Depression Coping Self-Efficacy Scale were used. The intervention group had significantly lower scores on the Beck Depression Inventory and Beck Hopelessness Scale at the post-test and 3-month follow-up; they had higher scores on the Depression Coping Self-Efficacy Scale at the 3-month follow-up when compared with the control group. The study was conducted at only one psychiatry clinic. The intervention and control group patients were at the clinic at the same time and influenced each other. Moreover, because clinical routines were in progress during the study, the results cannot only be attributed to nursing interventions. Nursing models offer guidance for the care provided. Practices based on the models return more efficient and systematic caregiving results with fewer health problems. Gordon's Functional Health Pattern Model was effective in improving the health of people with depression and could be introduced as routine care with ongoing evaluation in psychiatric clinics. More research is needed to evaluate Gordon's Nursing Model effect on people with depression. Future

Tidal flow separation at protruding beach nourishments

NARCIS (Netherlands)

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

2016-01-01

In recent years, the application of large-scale beach nourishments has been discussed, with the Sand Motor in the Netherlands as the first real-world example. Such protruding beach nourishments have an impact on tidal currents, potentially leading to tidal flow separation and the generation of tidal

Fundamental care guided by the Careful Nursing Philosophy and Professional Practice Model©.

Science.gov (United States)

Meehan, Therese Connell; Timmins, Fiona; Burke, Jacqueline

2018-02-05

To propose the Careful Nursing Philosophy and Professional Practice Model © as a conceptual and practice solution to current fundamental nursing care erosion and deficits. There is growing awareness of the crucial importance of fundamental care. Efforts are underway to heighten nurses' awareness of values that motivate fundamental care and thereby increase their attention to effective provision of fundamental care. However, there remains a need for nursing frameworks which motivate nurses to bring fundamental care values to life in their practice and strengthen their commitment to provide fundamental care. This descriptive position paper builds on the Careful Nursing Philosophy and Professional Practice Model © (Careful Nursing). Careful Nursing elaborates explicit nursing values and addresses both relational and pragmatic aspects of nursing practice, offering an ideal guide to provision of fundamental nursing care. A comparative alignment approach is used to review the capacity of Careful Nursing to address fundamentals of nursing care. Careful Nursing provides a value-based comprehensive and practical framework which can strengthen clinical nurses' ability to articulate and control their practice and, thereby, more effectively fulfil their responsibility to provide fundamental care and measure its effectiveness. This explicitly value-based nursing philosophy and professional practice model offers nurses a comprehensive, pragmatic and engaging framework designed to strengthen their control over their practice and ability to provide high-quality fundamental nursing care. © 2018 John Wiley & Sons Ltd.

Tidal heating and mass loss in neutron star binaries - Implications for gamma-ray burst models

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Meszaros, P.; Rees, M. J.

1992-01-01

A neutron star in a close binary orbit around another neutron star (or stellar-mass black hole) spirals inward owing to gravitational radiation. We discuss the effects of tidal dissipation during this process. Tidal energy dissipated in the neutron star's core escapes mainly as neutrinos, but heating of the crust, and outward diffusion of photons, blows off the outer layers of the star. This photon-driven mass loss precedes the final coalescence. The presence of this eject material impedes the escape of gamma-rays created via neutrino interactions. If an e(+) - e(-) fireball, created in the late stages of coalescence, were loaded with (or surrounded by) material with the mean column density of the ejecta, it could not be an efficient source of gamma-rays. Models for cosmologically distant gamma-rays burst that involve neutron stars must therefore be anisotropic, so that the fireball expands preferentially in directions where the column density of previously blown-off material is far below the spherically averaged value which we have calculated. Some possible 'scenarios' along these lines are briefly discussed.

Transverse structure of tidal flow, residual flow and sediment concentration in estuaries: sensitivity to tidal forcing and water depth

NARCIS (Netherlands)

Huijts, K.M.H.|info:eu-repo/dai/nl/304831867; de Swart, H.E.|info:eu-repo/dai/nl/073449725; Schramkowski, G.P.; Schuttelaars, H.M.

2011-01-01

An analytical and a numerical model are used to understand the response of velocity and sediment distributions over Gaussian-shaped estuarine cross-sections to changes in tidal forcing and water depth. The estuaries considered here are characterized by strong mixing and a relatively weak

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.

A potential flow 2-D vortex panel model: Applications to vertical axis straight blade tidal turbine

International Nuclear Information System (INIS)

Wang, L.B.; Zhang, L.; Zeng, N.D.

2007-01-01

A potential flow 2-D vortex panel model (VPM2D) for unsteady hydrodynamics calculation of the vertical axis straight blade variable pitch turbine was given for tidal streams energy conversion. Numerical results of predicted instantaneous blade forces and wake flow of the rotor showed good agreement with the test data. The model was also compared with the previous classic free vortex model (V-DART) and vortex method combined with finite element analysis (FEVDTM). It showed that the present model was much better than the former, less complex than the latter and suitable for designing and optimization of the vertical axis straight blade turbine

Development of an Instructional Quality Assurance Model in Nursing Science

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Ajpru, Haruthai; Pasiphol, Shotiga; Wongwanich, Suwimon

2011-01-01

The purpose of this study was to develop an instructional quality assurance model in nursing science. The study was divided into 3 phases; (1) to study the information for instructional quality assurance model development (2) to develop an instructional quality assurance model in nursing science and (3) to audit and the assessment of the developed…

Hierarchical Bayesian calibration of tidal orbit decay rates among hot Jupiters

Science.gov (United States)

Collier Cameron, Andrew; Jardine, Moira

2018-05-01

Transiting hot Jupiters occupy a wedge-shaped region in the mass ratio-orbital separation diagram. Its upper boundary is eroded by tidal spiral-in of massive, close-in planets and is sensitive to the stellar tidal dissipation parameter Q_s^'. We develop a simple generative model of the orbital separation distribution of the known population of transiting hot Jupiters, subject to tidal orbital decay, XUV-driven evaporation and observational selection bias. From the joint likelihood of the observed orbital separations of hot Jupiters discovered in ground-based wide-field transit surveys, measured with respect to the hyperparameters of the underlying population model, we recover narrow posterior probability distributions for Q_s^' in two different tidal forcing frequency regimes. We validate the method using mock samples of transiting planets with known tidal parameters. We find that Q_s^' and its temperature dependence are retrieved reliably over five orders of magnitude in Q_s^'. A large sample of hot Jupiters from small-aperture ground-based surveys yields log _{10} Q_s^' }=(8.26± 0.14) for 223 systems in the equilibrium-tide regime. We detect no significant dependence of Q_s^' on stellar effective temperature. A further 19 systems in the dynamical-tide regime yield log _{10} Q_s^' }=7.3± 0.4, indicating stronger coupling. Detection probabilities for transiting planets at a given orbital separation scale inversely with the increase in their tidal migration rates since birth. The resulting bias towards younger systems explains why the surface gravities of hot Jupiters correlate with their host stars' chromospheric emission fluxes. We predict departures from a linear transit-timing ephemeris of less than 4 s for WASP-18 over a 20-yr baseline.

Enceladus's crust as a non-uniform thin shell: I tidal deformations

Science.gov (United States)

Beuthe, Mikael

2018-03-01

The geologic activity at Enceladus's south pole remains unexplained, though tidal deformations are probably the ultimate cause. Recent gravity and libration data indicate that Enceladus's icy crust floats on a global ocean, is rather thin, and has a strongly non-uniform thickness. Tidal effects are enhanced by crustal thinning at the south pole, so that realistic models of tidal tectonics and dissipation should take into account the lateral variations of shell structure. I construct here the theory of non-uniform viscoelastic thin shells, allowing for depth-dependent rheology and large lateral variations of shell thickness and rheology. Coupling to tides yields two 2D linear partial differential equations of the fourth order on the sphere which take into account self-gravity, density stratification below the shell, and core viscoelasticity. If the shell is laterally uniform, the solution agrees with analytical formulas for tidal Love numbers; errors on displacements and stresses are less than 5% and 15%, respectively, if the thickness is less than 10% of the radius. If the shell is non-uniform, the tidal thin shell equations are solved as a system of coupled linear equations in a spherical harmonic basis. Compared to finite element models, thin shell predictions are similar for the deformations due to Enceladus's pressurized ocean, but differ for the tides of Ganymede. If Enceladus's shell is conductive with isostatic thickness variations, surface stresses are approximately inversely proportional to the local shell thickness. The radial tide is only moderately enhanced at the south pole. The combination of crustal thinning and convection below the poles can amplify south polar stresses by a factor of 10, but it cannot explain the apparent time lag between the maximum plume brightness and the opening of tiger stripes. In a second paper, I will study the impact of a non-uniform crust on tidal dissipation.

Instructional Storytelling: Application of the Clinical Judgment Model in Nursing.

Science.gov (United States)

Timbrell, Jessica

2017-05-01

Little is known about the teaching and learning implications of instructional storytelling (IST) in nursing education or its potential connection to nursing theory. The literature establishes storytelling as a powerful teaching-learning method in the educational, business, humanities, and health sectors, but little exploration exists that is specific to nursing. An example of a story demonstrating application of the domains of Tanner's clinical judgment model links storytelling with learning outcomes appropriate for the novice nursing student. Application of Tanner's clinical judgment model offers consistency of learning experience while preserving the creativity inherent in IST. Further research into student learning outcomes achievement using IST is warranted as a step toward establishing best practices with IST in nursing education. [J Nurs Educ. 2017;56(5):305-308.]. Copyright 2017, SLACK Incorporated.

ENHANCED OFF-CENTER STELLAR TIDAL DISRUPTIONS BY SUPERMASSIVE BLACK HOLES IN MERGING GALAXIES

International Nuclear Information System (INIS)

Liu, F. K.; Chen, Xian

2013-01-01

Off-center stellar tidal disruption flares have been suggested to be a powerful probe of recoiling supermassive black holes (SMBHs) out of galactic centers due to anisotropic gravitational wave radiations. However, off-center tidal flares can also be produced by SMBHs in merging galaxies. In this paper, we computed the tidal flare rates by dual SMBHs in two merging galaxies before the SMBHs become self-gravitationally bounded. We employ an analytical model to calculate the tidal loss-cone feeding rates for both SMBHs, taking into account two-body relaxation of stars, tidal perturbations by the companion galaxy, and chaotic stellar orbits in triaxial gravitational potential. We show that for typical SMBHs with masses 10 7 M ☉ , the loss-cone feeding rates are enhanced by mergers up to Γ ∼ 10 –2 yr –1 , about two orders of magnitude higher than those by single SMBHs in isolated galaxies and about four orders of magnitude higher than those by recoiling SMBHs. The enhancements are mainly due to tidal perturbations by the companion galaxy. We suggest that off-center tidal flares are overwhelmed by those from merging galaxies, making the identification of recoiling SMBHs challenging. Based on the calculated rates, we estimate the relative contributions of tidal flare events by single, binary, and dual SMBH systems during cosmic time. Our calculations show that the off-center tidal disruption flares by un-bound SMBHs in merging galaxies contribute a fraction comparable to that by single SMBHs in isolated galaxies. We conclude that off-center tidal disruptions are powerful tracers of the merging history of galaxies and SMBHs.

On summer stratification and tidal mixing in the Taiwan Strait

Science.gov (United States)

Zhu, Jia; Hu, Jianyu; Liu, Zhiyu

2013-06-01

On continental shelves, a front that separates the sea into well-mixed and stratified zones is usually formed in warm seasons due to spatial variations of tidal mixing. In this paper, using eight years of in situ hydrographic observations, satellite images of sea surface temperature (SST) and chlorophyll- a (Chl- a) concentration, and results of a tidal model, we investigate summer stratification in the Taiwan Strait and its dependence on tidal mixing, upwelling, and river diluted water plumes. In most regions of the strait the dominant role of tidal mixing in determining the thermohaline structure is confirmed by the correlation between the two; there are some regions, however, where thermohaline structure varies in different ways owing to significant influences of upwelling and river diluted water plumes. The well-mixed regions are mainly distributed on the Taiwan Bank and in the offshore regions off the Dongshan Island, Nanao Island, and Pingtan Island, while the northern and central Taiwan Strait and the region south of the Taiwan Bank are stratified. The critical Simpson-Hunter parameter for the region is estimated to be 1.78.

A Unified Model for Tidal Disruption Events

Science.gov (United States)

Dai, Lixin; McKinney, Jonathan C.; Roth, Nathaniel; Ramirez-Ruiz, Enrico; Miller, M. Coleman

2018-06-01

In the past few years wide-field optical and UV transient surveys and X-ray telescopes have allowed us to identify a few dozen candidate tidal disruption events (TDEs). While in theory the physical processes in TDEs are ubiquitous, a few distinct classes of TDEs have been observed. Some TDEs radiate mainly in NUV/optical, while others produce prominent X-rays. Moreover, relativistic jets have been observed in only a handful of TDEs. This diversity might be related to the details of the super-Eddington accretion and emission physics relevant to TDE disks. In this Letter, we utilize novel three-dimensional general relativistic radiation magnetohydrodynamics simulations to study the super-Eddington compact disk phase expected in TDEs. Consistent with previous studies, geometrically thick disks, wide-angle optically thick fast outflows, and relativistic jets are produced. The outflow density and velocity depend sensitively on the inclination angle, and hence so does the reprocessing of emission produced from the inner disk. We then use Monte Carlo radiative transfer to calculate the reprocessed spectra and find that that the observed ratio of optical to X-ray fluxes increases with increasing inclination angle. This naturally leads to a unified model for different classes of TDEs in which the spectral properties of the TDE depend mainly on the viewing angle of the observer with respect to the orientation of the disk.

Predicting long-term and short-term tidal flat morphodynamics using a dynamic equilibrium theory

NARCIS (Netherlands)

Hu, Z.; Wang, Z.B.; Zitman, T.J.; Stive, M.J.F.; Bouma, T.J.

2015-01-01

Dynamic equilibrium theory is a fruitful concept, which we use to systematically explain the tidal flat morphodynamic response to tidal currents, wind waves, sediment supply, and other sedimentological drivers. This theory stems from a simple analytical model that derives the tide- or wave-dominated

The use of modeling and suspended sediment concentration measurements for quantifying net suspended sediment transport through a large tidally dominated inlet

Science.gov (United States)

Erikson, Li H.; Wright, Scott A.; Elias, Edwin; Hanes, Daniel M.; Schoellhamer, David H.; Largier, John; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

2013-01-01

Sediment exchange at large energetic inlets is often difficult to quantify due complex flows, massive amounts of water and sediment exchange, and environmental conditions limiting long-term data collection. In an effort to better quantify such exchange this study investigated the use of suspended sediment concentrations (SSC) measured at an offsite location as a surrogate for sediment exchange at the tidally dominated Golden Gate inlet in San Francisco, CA. A numerical model was calibrated and validated against water and suspended sediment flux measured during a spring–neap tide cycle across the Golden Gate. The model was then run for five months and net exchange was calculated on a tidal time-scale and compared to SSC measurements at the Alcatraz monitoring site located in Central San Francisco Bay ~ 5 km from the Golden Gate. Numerically modeled tide averaged flux across the Golden Gate compared well (r2 = 0.86, p-value

Testing the social cognitive career theory in Thai nurses' interest to become nurse educators: A structural equation modeling analysis.

Science.gov (United States)

Thungjaroenkul, Petsunee; G Cummings, Greta; Tate, Kaitlyn

2016-09-01

A shortage of nurse educators generates a systemic problem in nursing education. A model to develop interventions directed at enhancing graduate nursing student interest in assuming a future faculty role is needed. This study used a social cognitive career theory perspective to examine the effects of past performance in teaching and supervision, social influence, observing others teaching, perceived task demands for nurse educators, self-efficacy, and outcome expectations on Thai graduate nursing students' (n=236) interest to become a nurse educator. Results of structural equation modeling analyses revealed that social influence and past performance in teaching and supervision had significant effects on interest to become a nurse educator when mediated by self-efficacy and outcome expectations. Observing others teaching and perceived task demands for nurse educators did not significantly predict interest in faculty roles. These findings provide new knowledge about factors and their influence on the development of interest to assume faculty roles. Implications for nursing education include the design of feasible graduate curricula that enhance students' abilities in faculty role and increases valuation of teaching careers. Copyright © 2016 Elsevier Ltd. All rights reserved.

Similarity and accuracy of mental models formed during nursing handovers: A concept mapping approach.

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Drach-Zahavy, Anat; Broyer, Chaya; Dagan, Efrat

2017-09-01

Shared mental models are crucial for constructing mutual understanding of the patient's condition during a clinical handover. Yet, scant research, if any, has empirically explored mental models of the parties involved in a clinical handover. This study aimed to examine the similarities among mental models of incoming and outgoing nurses, and to test their accuracy by comparing them with mental models of expert nurses. A cross-sectional study, exploring nurses' mental models via the concept mapping technique. 40 clinical handovers. Data were collected via concept mapping of the incoming, outgoing, and expert nurses' mental models (total of 120 concept maps). Similarity and accuracy for concepts and associations indexes were calculated to compare the different maps. About one fifth of the concepts emerged in both outgoing and incoming nurses' concept maps (concept similarity=23%±10.6). Concept accuracy indexes were 35%±18.8 for incoming and 62%±19.6 for outgoing nurses' maps. Although incoming nurses absorbed fewer number of concepts and associations (23% and 12%, respectively), they partially closed the gap (35% and 22%, respectively) relative to expert nurses' maps. The correlations between concept similarities, and incoming as well as outgoing nurses' concept accuracy, were significant (r=0.43, p<0.01; r=0.68 p<0.01, respectively). Finally, in 90% of the maps, outgoing nurses added information concerning the processes enacted during the shift, beyond the expert nurses' gold standard. Two seemingly contradicting processes in the handover were identified. "Information loss", captured by the low similarity indexes among the mental models of incoming and outgoing nurses; and "information restoration", based on accuracy measures indexes among the mental models of the incoming nurses. Based on mental model theory, we propose possible explanations for these processes and derive implications for how to improve a clinical handover. Copyright © 2017 Elsevier Ltd. All

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).

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.

High resolution multibeam and hydrodynamic datasets of tidal channels and inlets of the Venice Lagoon

Science.gov (United States)

Madricardo, Fantina; Foglini, Federica; Kruss, Aleksandra; Ferrarin, Christian; Pizzeghello, Nicola Marco; Murri, Chiara; Rossi, Monica; Bajo, Marco; Bellafiore, Debora; Campiani, Elisabetta; Fogarin, Stefano; Grande, Valentina; Janowski, Lukasz; Keppel, Erica; Leidi, Elisa; Lorenzetti, Giuliano; Maicu, Francesco; Maselli, Vittorio; Mercorella, Alessandra; Montereale Gavazzi, Giacomo; Minuzzo, Tiziano; Pellegrini, Claudio; Petrizzo, Antonio; Prampolini, Mariacristina; Remia, Alessandro; Rizzetto, Federica; Rovere, Marzia; Sarretta, Alessandro; Sigovini, Marco; Sinapi, Luigi; Umgiesser, Georg; Trincardi, Fabio

2017-09-01

Tidal channels are crucial for the functioning of wetlands, though their morphological properties, which are relevant for seafloor habitats and flow, have been understudied so far. Here, we release a dataset composed of Digital Terrain Models (DTMs) extracted from a total of 2,500 linear kilometres of high-resolution multibeam echosounder (MBES) data collected in 2013 covering the entire network of tidal channels and inlets of the Venice Lagoon, Italy. The dataset comprises also the backscatter (BS) data, which reflect the acoustic properties of the seafloor, and the tidal current fields simulated by means of a high-resolution three-dimensional unstructured hydrodynamic model. The DTMs and the current fields help define how morphological and benthic properties of tidal channels are affected by the action of currents. These data are of potential broad interest not only to geomorphologists, oceanographers and ecologists studying the morphology, hydrodynamics, sediment transport and benthic habitats of tidal environments, but also to coastal engineers and stakeholders for cost-effective monitoring and sustainable management of this peculiar shallow coastal system.

Content Validity of a Psychotherapeutic Intervention Model in Nursing: A Modified e-Delphi Study.

Science.gov (United States)

Sampaio, Francisco Miguel Correia; Sequeira, Carlos; Lluch Canut, Teresa

2017-04-01

To estimate the content validity of a psychotherapeutic intervention model in nursing. Mental health nurses encounter great extrinsic difficulties when it comes to providing psychotherapeutic interventions due to the fact that they are not allowed to perform such practice in some countries. In this light, the pursuit of a psychotherapeutic intervention model in nursing seems germane to guide the professionals' psychotherapeutic practice, contributing hereof to increase mental health nurses' professional autonomy. Modified e-Delphi. Data were collected from October 2015 to January 2016 by means of three rounds of online questionnaires. The initial questionnaire was structured into five sections: general structure of the model, patients' exclusion criteria, assessment framework, nursing diagnoses, and nursing psychotherapeutic interventions. From the 42 experts invited, at least twenty (20) participated in each round. The experts achieved consensus with regard to the conclusion that nursing psychotherapeutic interventions should always seek to address a nursing diagnosis. These defined furthermore that a psychotherapeutic intervention model in nursing should be exercised by means of 3 to 12 sessions using Nursing Interventions Classification (NIC) as a resource. Finally, experts deemed that the model should follow the principles of integrative psychotherapy, so that techniques from different schools of psychotherapy could therefore be used in conjunction to promote the resolution of a nursing diagnosis. Achieving consensus about the structure of a psychotherapeutic intervention model in nursing is imperative to guide nurses in the provision of nursing psychotherapeutic interventions and to enable an effective evaluation of the health gains associated with its implementation. Copyright © 2016 Elsevier Inc. All rights reserved.

Resonant Tidal Excitation of Internal Waves in the Earth's Fluid Core

Science.gov (United States)

Tyler, Robert H.; Kuang, Weijia

2014-01-01

It has long been speculated that there is a stably stratified layer below the core-mantle boundary, and two recent studies have improved the constraints on the parameters describing this stratification. Here we consider the dynamical implications of this layer using a simplified model. We first show that the stratification in this surface layer has sensitive control over the rate at which tidal energy is transferred to the core. We then show that when the stratification parameters from the recent studies are used in this model, a resonant configuration arrives whereby tidal forces perform elevated rates of work in exciting core flow. Specifically, the internal wave speed derived from the two independent studies (150 and 155 m/s) are in remarkable agreement with the speed (152 m/s) required for excitation of the primary normal mode of oscillation as calculated from full solutions of the Laplace Tidal Equations applied to a reduced-gravity idealized model representing the stratified layer. In evaluating this agreement it is noteworthy that the idealized model assumed may be regarded as the most reduced representation of the stratified dynamics of the layer, in that there are no non-essential dynamical terms in the governing equations assumed. While it is certainly possible that a more realistic treatment may require additional dynamical terms or coupling, it is also clear that this reduced representation includes no freedom for coercing the correlation described. This suggests that one must accept either (1) that tidal forces resonantly excite core flow and this is predicted by a simple model or (2) that either the independent estimates or the dynamical model does not accurately portray the core surface layer and there has simply been an unlikely coincidence between three estimates of a stratification parameter which would otherwise have a broad plausible range.

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

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

Modeled CO2 Emissions from Coastal Wetland Transitions to Other Land Uses: Tidal Marshes, Mangrove Forests, and Seagrass Beds

Directory of Open Access Journals (Sweden)

Catherine E. Lovelock

2017-05-01

Full Text Available The sediments of coastal wetlands contain large stores of carbon which are vulnerable to oxidation once disturbed, resulting in high levels of CO2 emissions that may be avoided if coastal ecosystems are conserved or restored. We used a simple model to estimate CO2 emissions from mangrove forests, seagrass beds, and tidal marshes based on known decomposition rates for organic matter in these ecosystems under either oxic or anoxic conditions combined with assumptions of the proportion of sediment carbon being deposited in either oxic or anoxic environments following a disturbance of the habitat. Our model found that over 40 years after disturbance the cumulative CO2 emitted from tidal marshes, mangrove forests, and seagrass beds were ~70–80% of the initial carbon stocks in the top meter of the sediment. Comparison of our estimates of CO2 emissions with empirical studies suggests that (1 assuming 50% of organic material moves to an oxic environment after disturbance gives rise to estimates that are similar to CO2 emissions reported for tidal marshes; (2 field measurements of CO2 emissions in disturbed mangrove forests were generally higher than our modeled emissions that assumed 50% of organic matter was deposited in oxic conditions, suggesting higher proportions of organic matter may be exposed to oxic conditions after disturbance in mangrove ecosystems; and (3 the generally low observed rates of CO2 emissions from disturbed seagrasses compared to our estimates, assuming removal of 50% of the organic matter to oxic environments, suggests that lower proportions may be exposed to oxic conditions in seagrass ecosystems. There are significant gaps in our knowledge of the fate of wetland sediment carbon in the marine environment after disturbance. Greater knowledge of the distribution, form, decomposition, and emission rates of wetland sediment carbon after disturbance would help to improve models.

Statistical correction of lidar-derived digital elevation models with multispectral airborne imagery in tidal marshes

Science.gov (United States)

Buffington, Kevin J.; Dugger, Bruce D.; Thorne, Karen M.; Takekawa, John Y.

2016-01-01

Airborne light detection and ranging (lidar) is a valuable tool for collecting large amounts of elevation data across large areas; however, the limited ability to penetrate dense vegetation with lidar hinders its usefulness for measuring tidal marsh platforms. Methods to correct lidar elevation data are available, but a reliable method that requires limited field work and maintains spatial resolution is lacking. We present a novel method, the Lidar Elevation Adjustment with NDVI (LEAN), to correct lidar digital elevation models (DEMs) with vegetation indices from readily available multispectral airborne imagery (NAIP) and RTK-GPS surveys. Using 17 study sites along the Pacific coast of the U.S., we achieved an average root mean squared error (RMSE) of 0.072 m, with a 40–75% improvement in accuracy from the lidar bare earth DEM. Results from our method compared favorably with results from three other methods (minimum-bin gridding, mean error correction, and vegetation correction factors), and a power analysis applying our extensive RTK-GPS dataset showed that on average 118 points were necessary to calibrate a site-specific correction model for tidal marshes along the Pacific coast. By using available imagery and with minimal field surveys, we showed that lidar-derived DEMs can be adjusted for greater accuracy while maintaining high (1 m) resolution.

Widespread infilling of tidal channels and navigable waterways in human-modified tidal deltaplain of southwest Bangladesh

Directory of Open Access Journals (Sweden)

Carol Wilson

2017-12-01

Full Text Available Since the 1960s, ~5000 km2 of tidal deltaplain in southwest Bangladesh has been embanked and converted to densely inhabited, agricultural islands (i.e., polders. This landscape is juxtaposed to the adjacent Sundarbans, a pristine mangrove forest, both well connected by a dense network of tidal channels that effectively convey water and sediment throughout the region. The extensive embanking in poldered areas, however, has greatly reduced the tidal prism (i.e., volume of water transported through local channels. We reveal that >600 km of these major waterways have infilled in recent decades, converting to land through enhanced sedimentation and the direct blocking of waterways by embankments and sluice gates. Nearly all of the observed closures (~98% have occurred along the embanked polder systems, with no comparable changes occurring in channels of the Sundarbans (<2% change. We attribute most of the channel infilling to the local reduction of tidal prism in poldered areas and the associated decline in current velocities. The infilled channels account for ~90 km2 of new land in the last 40–50 years, the rate of which, ~2 km2/yr, offsets the 4 km2/yr that is eroded at the coast, and is equivalent to ~20% of the new land produced naturally at the Ganges-Brahmaputra tidal rivermouth. Most of this new land, called ‘khas’ in Bengali, has been reclaimed for agriculture or aquaculture, contributing to the local economy. However, benefits are tempered by the loss of navigable waterways for commerce, transportation, and fishing, as well as the forced rerouting of tidal waters and sediments necessary to sustain this low-lying landscape against rising sea level. A more sustainable delta will require detailed knowledge of the consequences of these hydrodynamic changes to support more scientifically-grounded management of water, sediment, and tidal energy distribution.

Development of an International School Nurse Asthma Care Coordination Model

Science.gov (United States)

Garwick, Ann W.; Svavarsdóttir, Erla Kolbrun; Seppelt, Ann M.; Looman, Wendy S.; Anderson, Lori S.; Örlygsdóttir, Brynja

2015-01-01

Aim To identify and compare how school nurses in Reykjavik, Iceland and St. Paul, Minnesota coordinated care for youth with asthma (ages 10–18) and to develop an asthma school nurse care coordination model. Background Little is known about how school nurses coordinate care for youth with asthma in different countries. Design A qualitative descriptive study design using focus group data. Methods Six focus groups with 32 school nurses were conducted in Reykjavik (n=17) and St. Paul (n=15) using the same protocol between September 2008 – January 2009. Descriptive content analytic and constant comparison strategies were used to categorize and compare how school nurses coordinated care, which resulted in the development of an International School Nurse Asthma Care Coordination Model. Findings Participants in both countries spontaneously described a similar asthma care coordination process that involved information gathering, assessing risk for asthma episodes, prioritizing health care needs and anticipating and planning for student needs at the individual and school levels. This process informed how they individualized symptom management, case management and/or asthma education. School nurses played a pivotal part in collaborating with families, school and health care professionals to ensure quality care for youth with asthma. Conclusions Results indicate a high level of complexity in school nurses’ approaches to asthma care coordination that were responsive to the diverse and changing needs of students in school settings. The conceptual model derived provides a framework for investigators to use in examining the asthma care coordination process of school nurses in other geographic locations. PMID:25223389

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.

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.

TIDAL LIMITS TO PLANETARY HABITABILITY

International Nuclear Information System (INIS)

Barnes, Rory; Jackson, Brian; Greenberg, Richard; Raymond, Sean N.

2009-01-01

The habitable zones (HZs) of main-sequence stars have traditionally been defined as the range of orbits that intercept the appropriate amount of stellar flux to permit surface water on a planet. Terrestrial exoplanets discovered to orbit M stars in these zones, which are close-in due to decreased stellar luminosity, may also undergo significant tidal heating. Tidal heating may span a wide range for terrestrial exoplanets and may significantly affect conditions near the surface. For example, if heating rates on an exoplanet are near or greater than that on Io (where tides drive volcanism that resurfaces the planet at least every 1 Myr) and produce similar surface conditions, then the development of life seems unlikely. On the other hand, if the tidal heating rate is less than the minimum to initiate plate tectonics, then CO 2 may not be recycled through subduction, leading to a runaway greenhouse that sterilizes the planet. These two cases represent potential boundaries to habitability and are presented along with the range of the traditional HZ for main-sequence, low-mass stars. We propose a revised HZ that incorporates both stellar insolation and tidal heating. We apply these criteria to GJ 581 d and find that it is in the traditional HZ, but its tidal heating alone may be insufficient for plate tectonics.

A one-dimensional biomorphodynamic model of tidal flats: Sediment sorting, marsh distribution, and carbon accumulation under sea level rise

Science.gov (United States)

Zhou, Zeng; Ye, Qinghua; Coco, Giovanni

2016-07-01

We develop a biomorphodynamic model to investigate sediment and vegetation dynamics on a schematic intertidal flat characterized by an initially well-mixed sand-mud mixture. Major interactions between tides, wind waves, salt marshes, sediment transport and sea level rise (SLR) are taken into account. For a bare flat under only tidal action, the model predicts a convex cross-shore profile with the surficial distribution of mud and sand on the upper and lower part of the intertidal flat, respectively. When wind waves are strong, the intertidal flat is highly eroded resulting in a concave profile near the high water mark. This behavior is pronouncedly altered when the intertidal flat is vegetated with the presence of salt marshes. Numerical results suggest that a considerable amount of mud can still remain in the vegetated region even when wave action is strong. A steeper transition zone forms at the boundary between salt marshes and bare flats because of the differential sediment deposition in the two neighboring regions. The inclusion of wind waves is found to considerably enhance the size of the marsh-edge transition zone. For the numerical experiments designed in this study, the profile shape and sediment sorting behavior of tidal flats are not significantly modified by a gradual rising sea level. However, the impacts of SLR on vegetated tidal flats are still manifold: (a) driving the landward migration of intertidal zone and salt marshes; (b) enhancing sediment erosion on intertidal flats; and (c) drowning salt marshes under limited sediment supply with the constrain of seawalls. Finally, model results suggest that organic carbon accumulation on marshlands may be enhanced with an increasing SLR rate provided that salt marshes are not drowned.

Implementation of a documentation model comprising nursing terminologies--theoretical and methodological issues.

Science.gov (United States)

von Krogh, Gunn; Nåden, Dagfinn

2008-04-01

To describe and discuss theoretical and methodological issues of implementation of a nursing services documentation model comprising NANDA nursing diagnoses, Nursing Intervention Classification and Nursing Outcome Classification terminologies. The model is developed for electronic patient record and was implemented in a psychiatric hospital on an organizational level and on five test wards in 2001-2005. The theory of Rogers guided the process of innovation, whereas the implementation procedure of McCloskey and Bulecheck combined with adult learning principals guided the test site implementation. The test wards managed in different degrees to adopt the model. Two wards succeeded fully, including a ward with high percentage of staff with interdisciplinary background. Better planning regarding the impact of the organization's innovative aptitude, the innovation strategies and the use of differentiated methods regarding the clinician's individual premises for learning nursing terminologies might have enhanced the adoption to the model. To better understand the nature of barriers and the importance of careful planning regarding the implementation of electronic patient record elements in nursing care services, focusing on nursing terminologies. Further to indicate how a theory and specific procedure can be used to guide the process of implementation throughout the different levels of management.

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 ...

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.

From Globular Clusters to Tidal Dwarfs: Structure Formation in the Tidal Tails of Merging Galaxies

Science.gov (United States)

Knierman, Karen A.; Gallagher, Sarah C.; Charlton, Jane C.; Hunsberger, Sally D.; Whitmore, Bradley; Kundu, Arunav; Hibbard, J. E.; Zaritsky, Dennis

2003-09-01

Using V and I images obtained with the Wide Field Planetary Camera 2 (WFPC2) of the Hubble Space Telescope, we investigate compact stellar structures within tidal tails. Six regions of tidal debris in the four classic ``Toomre sequence'' mergers: NGC 4038/39 (``Antennae''), NGC 3256, NGC 3921, and NGC 7252 (``Atoms for Peace'') have been studied in order to explore how the star formation depends on the local and global physical conditions. These mergers sample a range of stages in the evolutionary sequence and tails with and without embedded tidal dwarf galaxies. The six tails are found to contain a variety of stellar structures, with sizes ranging from those of globular clusters up to those of dwarf galaxies. From V and I WFPC2 images, we measure the luminosities and colors of the star clusters. NGC 3256 is found to have a large population of blue clusters (0.2<~V-I<~0.9), particularly in its western tail, similar to those found in the inner region of the merger. In contrast, NGC 4038/39 has no clusters in the observed region of the tail, only less luminous point sources likely to be individual stars. NGC 3921 and NGC 7252 have small populations of clusters along their tails. A significant cluster population is clearly associated with the prominent tidal dwarf candidates in the eastern and western tails of NGC 7252. The cluster-rich western tail of NGC 3256 is not distinguished from the others by its dynamical age or by its total H I mass. However, the mergers that have few clusters in the tail all have tidal dwarf galaxies, while NGC 3256 does not have prominent tidal dwarfs. We speculate that star formation in tidal tails may manifest itself either in small structures like clusters along the tail or in large structures such as dwarf galaxies, but not in both. Also, NGC 3256 has the highest star formation rate of the four mergers studied, which may contribute to the high number of star clusters in its tidal tails. Based in part on observations obtained with the

Comparison of Nursing Student and Instructor Preferences for Block and Nonblock Clinical Models.

Science.gov (United States)

Rohatinsky, Noelle; Chachula, Kathryn; Sedgwick, Monique; Press, Madeline M; Compton, Roslyn M; Lane, Brenda

2017-10-05

Clinical experiences are the hallmark of prelicensure nursing programs and assist students with applying nursing theory into practice. The literature is limited with respect to nursing student and instructor preferences for type of clinical model to facilitate student learning. This article explores these perceptions in the nursing programs of 5 universities located in 4 Western Canadian provinces. Findings support the use of both nonblock and block clinical models throughout nursing education programs.

Model of Emergency and Observation Nursing Services at the Community Health Center in East Java

Directory of Open Access Journals (Sweden)

Dwi Ananto Wibrata

2017-07-01

Full Text Available Public health centers as the spearhead of health services, also provide 'emergency and observation' nursing services, due to the high number of accidents in East Java. The purpose of this study was to develop the nurse's performance model in providing 'emergency and obeservation' nursing services at Puskesgadarsi ('Emergency and Observation' Community Health Center in East Java, using cross sectional design. The subjects of 120 nurses were selected by multi stage sampling technique. Data were collected through questionnaires and FGDs, and then analyzed using structural equation modeling to produce an model of ‘emergency and observation’ nursing service for nurses at Puskesgadarsi. Components of the model were reinforcing factors, personal factors, cognition factors, affection factors, commitment, interpersonal, reinforcement and nurse performance. Nurses can use this model in providing nursing services with due regard to their knowledge and skills, facilities and infrastructure, as well as interaction and self-reinforcement, so as to be able to perform nursing services 'emergency and observation' well.

Structural Equation Modeling of Cultural Competence of Nurses Caring for Foreign Patients.

Science.gov (United States)

Ahn, Jung-Won

2017-03-01

This study aimed to construct and test a hypothetical model including factors related to the cultural competence of nurses caring for foreign patients. The transcultural nursing immersion experience model and anxiety/uncertainty management theory were used to verify the paths between the variables. The exogenous variables were multicultural experience, ethnocentric attitude, and organizational cultural competence support. The endogenous variables were intercultural anxiety, intercultural uncertainty, coping strategy, and cultural competence. Participants were 275 nurses working in general hospitals in Seoul and Kyung-Gi Do, Korea. Each nurse in this study had experience of caring for over 10 foreign patients. Data were collected using a structured questionnaire and analyzed with SPSS statistical software with the added AMOS module. The overall fitness indices of the hypothetical model were a good fit. Multicultural experience, ethnocentric attitude, organizational cultural competence support, and intercultural uncertainty were found to have a direct and indirect effect on the cultural competence of nurses while coping strategy only had a direct effect. Intercultural anxiety did not have a significant effect on cultural competence. This model explained 59.1% of the variance in the nurses' cultural competence when caring for foreign patients. Nurses' cultural competence can be developed by offering multicultural nursing education, increasing direct/indirect multicultural experience, and sharing problem-solving experience to promote the coping ability of nurses. Organizational support can be achieved by preparing relevant personnel and resources. Subsequently, the quality of nursing care for foreign patients' will be ultimately improved. Copyright © 2017. Published by Elsevier B.V.

A new assessment model and tool for pediatric nurse practitioners.

Science.gov (United States)

Burns, C

1992-01-01

This article presents a comprehensive assessment model for pediatric nurse practitioner (PNP) practice that integrates familiar elements of the classical medical history, Gordon's Functional Health Patterns, and developmental fields into one system. This model drives the diagnostic reasoning process toward consideration of a broad range of disease, daily living (nursing diagnosis), and developmental diagnoses, which represents PNP practice better than the medical model does.

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

Regulatory, design and methodological impacts in determining tidal-in-stream power resource potential

International Nuclear Information System (INIS)

Atwater, Joel F.; Lawrence, Gregory A.

2011-01-01

Tidal-in-Stream energy has been heralded by many as a significant potential source for clean power, a scheme where kinetic energy is extracted from tidal currents. A number of estimates have suggested that tidal power may become a sizeable fraction of overall electricity generation, however these estimates have been largely based on a resource assessment methodology that dramatically oversimplifies the physical phenomenon at play. This paper develops a model that considers the effect of energy extraction on the bulk flow, showing that tidal energy inventories that assess solely kinetic energy flux may represent both an order-of-magnitude overestimation of the resource and a significant oversimplification of regulatory impacts. The interplay between the characteristics of a flow and the regulatory and economic issues will likely limit tidal power generation to levels significantly below the physical maximums. Permitted flow reduction, turbine design and staging of development all have significant and predictable impacts on the extractible resource. Energy planners must therefore understand these relationships in order to appropriately assess the magnitude of generation that can be realistically be produced from tidal energy. - Research highlights: → Inventorying kinetic energy is not appropriate for assessing the tidal energy potential and may overestimate the resource by orders of magnitude. → The physical maximum for tidal power extraction is 38% of the total fluid power of a channel and causes a flow reduction of 42%. → Any amount of tidal power generation will reduce the flow rate in a channel. → Limiting the permitted reduction in flow significantly reduces the available resource. → Turbine efficiency is important as extraneous resistance depletes the resource without providing power generation.

Conditions for tidal bore formation in convergent alluvial estuaries

Science.gov (United States)

Bonneton, Philippe; Filippini, Andrea Gilberto; Arpaia, Luca; Bonneton, Natalie; Ricchiuto, Mario

2016-04-01

Over the last decade there has been an increasing interest in tidal bore dynamics. However most studies have been focused on small-scale bore processes. The present paper describes the first quantitative study, at the estuary scale, of the conditions for tidal bore formation in convergent alluvial estuaries. When freshwater discharge and large-scale spatial variations of the estuary water depth can be neglected, tide propagation in such estuaries is controlled by three main dimensionless parameters: the nonlinearity parameter ε0 , the convergence ratio δ0 and the friction parameter ϕ0. In this paper we explore this dimensionless parameter space, in terms of tidal bore occurrence, from a database of 21 estuaries (8 tidal-bore estuaries and 13 non tidal-bore estuaries). The field data point out that tidal bores occur for convergence ratios close to the critical convergence δc. A new proposed definition of the friction parameter highlights a clear separation on the parameter plane (ϕ0,ε0) between tidal-bore estuaries and non tidal-bore estuaries. More specifically, we have established that tidal bores occur in convergent estuaries when the nonlinearity parameter is greater than a critical value, εc , which is an increasing function of the friction parameter ϕ0. This result has been confirmed by numerical simulations of the two-dimensional Saint Venant equations. The real-estuary observations and the numerical simulations also show that, contrary to what is generally assumed, tide amplification is not a necessary condition for tidal bore formation. The effect of freshwater discharge on tidal bore occurrence has been analyzed from the database acquired during three long-term campaigns carried out on the Gironde/Garonne estuary. We have shown that in the upper estuary the tidal bore intensity is mainly governed by the local dimensionless tide amplitude ε. The bore intensity is an increasing function of ε and this relationship does not depend on freshwater

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...

Model medication management process in Australian nursing homes using business process modeling.

Science.gov (United States)

Qian, Siyu; Yu, Ping

2013-01-01

One of the reasons for end user avoidance or rejection to use health information systems is poor alignment of the system with healthcare workflow, likely causing by system designers' lack of thorough understanding about healthcare process. Therefore, understanding the healthcare workflow is the essential first step for the design of optimal technologies that will enable care staff to complete the intended tasks faster and better. The often use of multiple or "high risk" medicines by older people in nursing homes has the potential to increase medication error rate. To facilitate the design of information systems with most potential to improve patient safety, this study aims to understand medication management process in nursing homes using business process modeling method. The paper presents study design and preliminary findings from interviewing two registered nurses, who were team leaders in two nursing homes. Although there were subtle differences in medication management between the two homes, major medication management activities were similar. Further field observation will be conducted. Based on the data collected from observations, an as-is process model for medication management will be developed.

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.

Modeling tidal marsh distribution with sea-level rise: evaluating the role of vegetation, sediment, and upland habitat in marsh resiliency.

Science.gov (United States)

Schile, Lisa M; Callaway, John C; Morris, James T; Stralberg, Diana; Parker, V Thomas; Kelly, Maggi

2014-01-01

Tidal marshes maintain elevation relative to sea level through accumulation of mineral and organic matter, yet this dynamic accumulation feedback mechanism has not been modeled widely in the context of accelerated sea-level rise. Uncertainties exist about tidal marsh resiliency to accelerated sea-level rise, reduced sediment supply, reduced plant productivity under increased inundation, and limited upland habitat for marsh migration. We examined marsh resiliency under these uncertainties using the Marsh Equilibrium Model, a mechanistic, elevation-based soil cohort model, using a rich data set of plant productivity and physical properties from sites across the estuarine salinity gradient. Four tidal marshes were chosen along this gradient: two islands and two with adjacent uplands. Varying century sea-level rise (52, 100, 165, 180 cm) and suspended sediment concentrations (100%, 50%, and 25% of current concentrations), we simulated marsh accretion across vegetated elevations for 100 years, applying the results to high spatial resolution digital elevation models to quantify potential changes in marsh distributions. At low rates of sea-level rise and mid-high sediment concentrations, all marshes maintained vegetated elevations indicative of mid/high marsh habitat. With century sea-level rise at 100 and 165 cm, marshes shifted to low marsh elevations; mid/high marsh elevations were found only in former uplands. At the highest century sea-level rise and lowest sediment concentrations, the island marshes became dominated by mudflat elevations. Under the same sediment concentrations, low salinity brackish marshes containing highly productive vegetation had slower elevation loss compared to more saline sites with lower productivity. A similar trend was documented when comparing against a marsh accretion model that did not model vegetation feedbacks. Elevation predictions using the Marsh Equilibrium Model highlight the importance of including vegetation responses to sea