scholarly journals On Natural Modulational Bandwidth of Deep-Water Surface Waves

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 67
Author(s):  
Alexander Babanin ◽  
Miguel Onorato ◽  
Luigi Cavaleri
Keyword(s):  
Deep Water ◽  
Water Surface ◽  
Laboratory Experiments ◽  
Wind Wave ◽  
Wave Spectra ◽  
Field Observations ◽  
Wave Steepness ◽  
Side Band ◽  
Wave Trains

We suggest that there exists a natural bandwidth of wave trains, including trains of wind-generated waves with a continuous spectrum, determined by their steepness. Based on laboratory experiments with monochromatic waves, we show that, if no side-band perturbations are imposed, the ratio between the wave steepness and bandwidth is restricted to certain limits. These limits are consistent with field observations of narrow-banded wind-wave spectra if a characteristic width of the spectral peak and average steepness are used. The role of the wind in such modulation is also discussed.

scholarly journals A sink host allows a specialist herbivore to persist in a seasonal source

2021 ◽  
Vol 288 (1958) ◽  
pp. 20211604
Author(s):  
Alicja Laska ◽  
Sara Magalhães ◽  
Mariusz Lewandowski ◽  
Ewa Puchalska ◽  
Kamila Karpicka-Ignatowska ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Laboratory Experiments ◽  
Field Observations ◽  
Stepping Stones ◽  
Specialist Herbivore ◽  
Negative Growth Rate ◽  
Evolutionary Rescue ◽  
Main Host ◽  
Negative Growth

In seasonal environments, sinks that are more persistent than sources may serve as temporal stepping stones for specialists. However, this possibility has to our knowledge, not been demonstrated to date, as such environments are thought to select for generalists, and the role of sinks, both in the field and in the laboratory, is difficult to document. Here, we used laboratory experiments to show that herbivorous arthropods associated with seasonally absent main (source) habitats can endure on a suboptimal (sink) host for several generations, albeit with a negative growth rate. Additionally, they dispersed towards this host less often than towards the main host and accepted it less often than the main host. Finally, repeated experimental evolution attempts revealed no adaptation to the suboptimal host. Nevertheless, field observations showed that arthropods are found in suboptimal habitats when the main habitat is unavailable. Together, these results show that evolutionary rescue in the suboptimal habitat is not possible. Instead, the sink habitat functions as a temporal stepping stone, allowing for the persistence of a specialist when the source habitat is gone.

scholarly journals Immunolocalization of deformed wing virus particles within the mite Varroa destructor

2008 ◽  
Vol 89 (7) ◽  
pp. 1685-1689 ◽  
Author(s):  
Ma. Teresa Santillán-Galicia ◽  
Raffaella Carzaniga ◽  
Brenda V. Ball ◽  
Peter G. Alderson
Keyword(s):  
Varroa Destructor ◽  
Laboratory Experiments ◽  
Field Observations ◽  
Pupal Development ◽  
Deformed Wing Virus ◽  
Faecal Pellets ◽  
Virus Particles ◽  
Midgut Lumen ◽  
Wing Deformation

Deformed wing virus (DWV) induces wing deformation when bees are infected during their pupal development. Field observations and laboratory experiments suggest that the mite Varroa destructor is a vector of the virus. Moreover, it has been stated that DWV replicates within this mite. In order to understand the role of V. destructor in the transmission of DWV, the objective of this work was to locate the sites of retention and/or replication of DWV within the mite by immunohistochemistry. There was no evidence that DWV was replicating in the mite as no tissues showed specific antibody binding to DWV. Also, there were no specific structures that could be suggested as retention sites. DWV was found only in the midgut lumen of V. destructor in structures resembling large, dense spheres, which were presumably faecal pellets.

Neural network approximations for nonlinear interactions in wind wave spectra: direct mapping for wind seas in deep water

2005 ◽  
Vol 8 (3) ◽  
pp. 253-278 ◽  
Author(s):  
Hendrik L. Tolman ◽  
Vladimir M. Krasnopolsky ◽  
Dmitry V. Chalikov
Keyword(s):  
Neural Network ◽  
Deep Water ◽  
Wind Wave ◽  
Wave Spectra ◽  
Nonlinear Interactions ◽  
Direct Mapping

scholarly journals On the Evolution of Different Types of Green Water Events

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1148
Author(s):  
Jassiel V. H. Fontes ◽  
Irving D. Hernández ◽  
Edgar Mendoza ◽  
Rodolfo Silva ◽  
Eliana Brandão da Silva ◽  
...  
Keyword(s):  
Water Surface ◽  
Early Stage ◽  
Dam Break ◽  
Green Water ◽  
Wave Steepness ◽  
Wave Flume ◽  
Initial Stage ◽  
Different Types ◽  
Wave Trains ◽  
First Time

Green water events may present different features in the initial stage of interaction with the deck of a structure. It is therefore important to investigate the evolution of different types of green water, since not all the events interact with the deck at the same time. In this paper, the evolution of three types of green water events (dam-break, plunging-dam-break, and hammer-fist) are studied. The water surface elevations and volumes over the deck in consecutive green water events, generated by incident [wave trains in a wave flume, were analyzed using image-based methods. The results show multiple-valued water surface elevations in the early stage of plunging-dam-break and hammer-fist type events. Detailed experimental measurements of this stage are shown for the first time. The effect of wave steepness on the duration of the events, maximum freeboard exceedance, and volumes were also investigated. Although the hammer-fist type showed high freeboard exceedances, the plunging-dam-break type presented the largest volumes over the deck. Some challenges for further assessments of green water propagation are reported.

scholarly journals The Role of Nonlinear Momentum Fluxes on the Evolution of Directional Wind-Wave Spectra

2011 ◽  
Vol 41 (4) ◽  
pp. 781-801 ◽  
Author(s):  
Donald T. Resio ◽  
Charles E. Long ◽  
William Perrie
Keyword(s):  
Energy Flux ◽  
Wind Wave ◽  
Stationary Solutions ◽  
Wave Spectra ◽  
Wave Interactions ◽  
Numerical Studies ◽  
Momentum Fluxes ◽  
Directional Distributions ◽  
Equilibrium Range

Abstract It has long been known that nonlinear wave–wave interactions produce stationary solutions related to constant energy flux through the equilibrium range when a deep-water spectrum follows an f−4 form, as has been verified in numerical studies in which spectra follow a constant angular spreading distribution. This paper shows that, although energy fluxes through such spectra remain essentially constant, momentum fluxes do not. On the other hand, if the angular distribution of a spectrum is allowed to behave in a manner consistent with observations, both the energy flux and the momentum flux tend to remain constant through a major portion of the spectrum. Thus, it appears that directional distributions of energy within wind-wave spectra adjust to a form consistent with nondivergent nonlinear fluxes, suggesting that these fluxes likely play a very prominent role in the evolution of directional spectra during wave generation.

The disintegration of wave trains on deep water Part 1. Theory

1967 ◽  
Vol 27 (3) ◽  
pp. 417-430 ◽  
Author(s):  
T. Brooke Benjamin ◽  
J. E. Feir
Keyword(s):  
Deep Water ◽  
Wave Train ◽  
Low Frequency ◽  
Periodic Wave ◽  
Wave Number ◽  
Fundamental Wave ◽  
Side Band ◽  
Wave Trains ◽  
The Stability ◽  
Deep Water Part

The phenomenon in question arises when a periodic progressive wave train with fundamental frequency ω is formed on deep water—say by radiation from an oscillating paddle—and there are also present residual wave motions at adjacent side-band frequencies ω(1 ± δ), such as would be generated if the movement of the paddle suffered a slight modulation at low frequency. In consequence of coupling through the non-linear boundary conditions at the free surface, energy is then transferred from the primary motion to the side bands at a rate that, as will be shown herein, can increase exponentially as the interaction proceeds. The result is that the wave train becomes highly irregular far from its origin, even when the departures from periodicity are scarcely detectable at the start.In this paper a theoretical investigation is made into the stability of periodic wave trains to small disturbances in the form of a pair of side-band modes, and Part 2 which will follow is an account of some experimental observations in accord with the present predictions. The main conclusion of the theory is that infinitesimal disturbances of the type considered will undergo unbounded magnification if \[ 0 < \delta \leqslant (\sqrt{2})ka, \] where k and a are the fundamental wave-number and amplitude of the perturbed wave train. The asymptotic rate of growth is a maximum for δ = ka.

Role of Internal Phosphorus Loading in Two Shallow, Productive Lakes in Alberta, Canada

1984 ◽  
Vol 41 (6) ◽  
pp. 845-855 ◽  
Author(s):  
E. T. Riley ◽  
E. E. Prepas
Keyword(s):  
Surface Water ◽  
Deep Water ◽  
Laboratory Experiments ◽  
Water Exchange ◽  
Sediment Cores ◽  
Internal Loading ◽  
Phosphorus Loading ◽  
Quantitative Estimates ◽  
Internal Phosphorus Loading

The contribution of internal loading from the sediments to the total phosphorus (TP) budget and to the [TP] in the surface water was investigated from May to November in Nakamun and Halfmoon lakes, Alberta. During the summer, Nakamun Lake was intermittently stratified and Halfmoon Lake was weakly, thermally stratified. During the stratified periods, water overlying the sediments was anoxic, TP levels increased in the deep water, and sediments were the main source of TP, contributing 1468 and 147 kg of TP to Nakamun and Halfmoon lakes, respectively. During these same periods, internal loading to Nakamun and Halfmoon lakes (12.7 and 15.6 mg∙m−2∙d−1, respectively) were slightly higher than the rates predicted from laboratory experiments on sediment cores (9.7 and 7.2 mg∙m−2∙d−1, respectively). Quantitative estimates of vertical water exchange in Nakamun Lake and in-lake TP budgets for both lakes indicated that phosphorus released from the sediments was transported to the surface water during mixing. After eight of the nine mixing events that immediatley followed stratified periods, [TP] increased 3–43% and 31–52% in the surf ace water of Nakamun and Halfmoon lakes, respectively.

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