Search results for "Shallow"

Flow resistance ofPosidonia oceanicain shallow water

2006

Management of coastal waters and lagoons by mathematical circulation models requires determination of the hydraulic resistance of submerged vegetation. A plant typical of sandy coastal bottoms in the Mediterranean Sea is Posidonia oceanica, which is constituted by very thin and flexible ribbon-like leaves, about 1 cm wide and up to 1.5 m long, and usually covers the bottom with a density of 500-1000 plants/ m2. From the hydraulic viewpoint, P. oceanica constitutes a particular roughness, because, as the velocity increases, the leaves bend more and more until they lie down on the bottom. Although P. oceanica is widespread, in the technical literature it is difficult to find indications about…

Finite-Element Modeling of Floodplain Flow

2000

A new methodology for a robust solution of the diffusive shallow water equations is proposed. The methodology splits the unknowns of the momentum and continuity equations into one kinematic and one parabolic component. The kinematic component is solved using the slope of the water level surface computed in the previous time-step and a zero-order approximation of the water head inside the mass-balance area around each node of the mesh. The parabolic component is found by applying a standard finite-element Galerkin procedure, where the source terms can be computed from the solution of the previous kinematic problem. A simple 1D case, with a known analytical solution, is used to test the accur…

Long time behavior for a dissipative shallow water model

2013

We consider the two-dimensional shallow water model derived by Levermore and Sammartino (Nonlinearity 14,2001), describing the motion of an incompressible fluid, confined in a shallow basin, with varying bottom topography. We construct the approximate inertial manifolds for the associated dynamical system and estimate its order. Finally, considering the whole domain R^2 and under suitable conditions on the time dependent forcing term, we prove the L^2 asymptotic decay of the weak solutions.

Diffusive Modeling of Aggradation and Degradation in Artificial Channels

2008

The unsteady flow and solid transport simulation problem in artificial channels is solved using a three-equation model, coupled with a local erosion law. The three equations are the water mass and momentum balance equations, as well as the total solid load balance equation. It is shown that even during severe hydrological events inertial terms can be neglected in the momentum equation without any substantial change in the solution sought. Empirical equilibrium formulas were used to estimate the solid load as a function of the flow variables. Local erosion, due to the scour generated at the jump between two channels connected at different bottom elevations, was estimated adapting a literatur…

Phytoplankton in the Physical Environment

2010

Grey matter reduction in the occipitotemporal cortex in Spanish children with dyslexia: A voxel-based morphometry study

2020

Abstract Structural and functional neuroimaging studies have reported brain alterations in occipitotemporal, temporoparietal, and left frontal areas in dyslexic patients. These areas have been linked to reading skill impairments, due to their involvement in word recognition and processing. However, most of the patients in these studies were speakers of languages with a deep orthography. In this study, we used voxel-based morphometry (VBM) to investigate brain differences in grey matter volume associated with a transparent language in a sample of 25 native Spanish participants (13 dyslexic and 12 non-dyslexic children). Results revealed a volume reduction in the left occipitotemporal cortex …

Lower and Middle Cambrian brachiopods from the Iberian Chains and Sierra Morena (Spain)

2021

Brachiopods from the Lower and Middle Cambrian of the Iberian Chains and Sierra Morena are described. The following taxa occur in the Iberian Chains: "Lingulella" sp., Redlichella cf. bohemica (Barrande), Dictyonina radioplicata sp. n., Micromitra sp., Trematobolus simplex (Vogel), Trematobolus borobiensis sp. n. and Jamesella sp. The taxa "Lingulella" sp. and Sibiria? sp. are reported from the Lower Cambrian of Sierra Morena. Brachiopods constitute several distinct associations: the relatively shallow water Trematobolus assemblage near the Lower-Middle Cambrian boundary interval is followed by the deeper Dictyonina­Redlichella assemblage. The alternation of these assemblages permit us to i…

Competition among introduced and indigenous submerged macrophytes in a southern mediterranean shallow system

2011

In Termini Imerese H. stipulacea has been recorded inside artificial basins, located near the harbour, built arranging breakwater barriers along the coast in order to protect the coastal road. From July until the beginning of November the seagrass formed beds with cover values ranging from 70% to 80%, and it was in contact either with the seagrass Cymodocea nodosa (Ucria) Ascherson (cover values of 20-25%) or the green alga Caulerpa prolifera (Forsskål) Lamouroux (cover values of 10-15%). H. stipulacea in good health conditions showed a clear competition strategy with C. nodosa as proved by registered cover values. But during natural denudations occurring in winter, C. racemosa var. cylindr…

Interactions among introduced and indigenous submerged macrophytes in a Mediterranean shallow system

2011

In Termini Imerese H. stipulacea has been recorded inside artificial basins, characterized by a sandy bottom (0.80‐2.5 m depth). H. stipulacea in good health conditions shows a competition strategy with C. nodosa. But during winter denudations, C. racemosa var. cylindracea seems to negatively interfere with the rhizomes of H. stipulacea.

Baraitser-Winter cerebrofrontofacial syndrome : Delineation of the spectrum in 42 cases

2015

International audience; Baraitser-Winter, Fryns-Aftimos and cerebrofrontofacial syndrome types 1 and 3 have recently been associated with heterozygous gain-of-function mutations in one of the two ubiquitous cytoplasmic actin-encoding genes ACTB and ACTG1 that encode beta- and gamma-actins. We present detailed phenotypic descriptions and neuroimaging on 36 patients analyzed by our group and six cases from the literature with a molecularly proven actinopathy (9 ACTG1 and 33 ACTB). The major clinical anomalies are striking dysmorphic facial features with hypertelorism, broad nose with large tip and prominent root, congenital non-myopathic ptosis, ridged metopic suture and arched eyebrows. Iris…