A framework of numerical models has been implemented and applied to the Venice Lagoon. The models consist of a state of the art hydrodynamic model for shallow areas and lagoons and a last generation ...wave model. With these models the bottom stress distribution during typical strong meteorological situations is studied.
Results show a good agreement of the computed bottom stress patterns and the empirical erosion and deposition rates found in the lagoon. The areas where wave action is responsible for sediment re-suspension are identified; they consist basically in the large shallow areas that are spread out all over the lagoon. This makes the wave action the most important erosion mechanism in the lagoon during typical strong winds.
Three scenarios of future climatic changes are simulated: an increase in the amplitude of the tidal oscillation, a global sea level rise and the combination of both. The results show that the most vulnerable parts of the lagoon are the flat regions close to the deeper channels. The erosion of these channel borders could be the cause of the filling of the deeper channels that then would need artificial dredging.
► We study the effect of ocean circulation on waves in the semi-enclosed Adriatic Sea. ► Numerical simulations are performed using COAWST modeling system on two grids of different resolutions (2.0 ...and 0.5km). ► The model errors are assessed with various types of observations: in situ and remotely sensed. ► The current induced variations on wave field are significant in storm conditions.
The effect on waves of the Wave–Current Interaction (WCI) process in the semi-enclosed Gulf of Venice (northern region of the Adriatic Sea) was investigated using the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system. COAWST relies on the ocean model ROMS (Regional Ocean Modeling System), the wave model SWAN (Simulating WAves Nearshore), and the CSTMS (Community Sediment Transport Modeling System) routines. The two-way data transfer between circulation and wave models was synchronous via MCT (Model Coupling Toolkit), with ROMS providing: current field, free surface elevation, and bathymetry to SWAN. For coupling, the 3-D current profiles were averaged using a formulation which integrated the near-surface velocity over a depth controlled by the spectral mean wavenumber. COAWST system was implemented on a parent grid (with horizontal resolution of 2.0km) covering the whole Adriatic Sea with one-way nesting to a child grid resolving the northern area (Gulf of Venice) at a resolution of 0.5km. The meteorological forcings provided by the operational meteorological model COSMO-I7 (a mesoscale model developed in the framework of the COSMO Consortium) were used to drive the modeling system in the period bracketing September 2010–August 2011. The adopted winds and the simulated waves were compared with observations at the CNR-ISMAR Acqua Alta oceanographic tower, located off the Venice littoral. Wave heights and sea surface winds were also compared with satellite-derived data. The analysis of WCI was performed on the child grid over the winter season (January–March 2011) with particular focus on the waves generated by prevailing and dominant winds blowing on the Adriatic Sea: Bora and Sirocco. Due to the variable wind direction with respect to the ocean current direction different effects on WCI were depicted, showing that within the northern Adriatic Sea the ocean–wave interactions are strongly dependent on the wind forcing direction. Further investigations reveal that, when applied to intense storms, the effect of coupling on waves results in variations of significant wave height up to 0.6m, with some areas experiencing significant increase/decrease of wave spectral energy for opposite/following currents respectively.
We study a class of complex vector fields defined on the two-torus of the form
L
=
∂
/
∂
t
+
(
a
(
x
,
t
)
+
i
b
(
x
,
t
)
)
∂
/
∂
x
,
a
,
b
∈
C
∞
(
T
2
;
R
)
,
b
≢
0
. We view
L
as an operator ...acting on smooth functions and present conditions for
L
to have either a closed range or a finite-codimensional range. Our results involve, besides condition (
P
) of Nirenberg and Treves, the behavior of
a
+
i
b
near each one-dimensional Sussmann orbit homotopic to the unit circle. One of the main goals of our work is to provide some clarification about the role played by the coefficient
a in the validity of the above properties of the range.
On étudie une classe de champs de vecteurs complexes definis sur le tore et de la forme
L
=
∂
/
∂
t
+
(
a
(
x
,
t
)
+
i
b
(
x
,
t
)
)
∂
/
∂
x
,
a
,
b
∈
C
∞
(
T
2
;
R
)
,
b
≢
0
. On considère
L
comme un opérateur defini sur les fonctions indéfiniment différentiables et on donne des conditions pour que l'image de
L
soit fermée et pour qu'elle soit aussi de codimension finie. Nos résultats utilisent la condition (
P
) de Nirenberg et Trèves ainsi que le comportement de
a
+
i
b
près de chaque orbite de Sussmann unidimensionnelle homotope au cercle unitaire. Un des buts principaux de notre article est de préciser le rôle joué par le coefficient
a dans la validité des proprietés de l'image ci-dessus.
This study was developed within the framework of a broad international project, ‘Ecological water quality assessment of the Alcantara (Italy), James (USA) and Guadalfeo (Spain) rivers using ...bioindicators’, established by the Center for Integrative Mediterranean Studies (CIMS), a collaborative research centre consisting of the University of Messina – Italy, Virginia Commonwealth University – USA, and the University of Cordoba – Spain. The primary objective of the study was the validation of a multi-disciplinary ecological approach at different taxonomic levels for biomonitoring of the Alcantara River (Sicily, Italy) using bioindicators. This study examined the primary physical, chemical and biological features of the river through an interdisciplinary and synoptic approach using bioindicators that included riparian plant physiology, the microbial, zooplanktonic and macroinvertebrate assemblages, Coleoptera (Insecta) and river hydrology. Sampling of the river and riparian areas was conducted at sites from the river’s headwaters to the mouth. The study provided information on the ecological status of the Alcantara River along its course and tested the use of a variety of bioindicators, rather than a single biotic or physicalattribute, to determine the river’s health.
Let L=∂/∂t+∑j=1N(aj+ibj)(t)∂/∂xj be a vector field defined on the torus TN+1≃RN+1/2πZN+1, where aj, bj are real-valued functions and belonging to the Gevrey class Gs(T1), s>1, for j=1,…,N. We present ...a complete characterization for the s-global solvability and s-global hypoellipticity of L. Our results are linked to Diophantine properties of the coefficients and, also, connectedness of certain sublevel sets.
During the austral summer 1997/1998, an oceanographic cruise was carried out on a large-scale grid in the Ross Sea. In this contribution, we focused our attention on the coastal area from the Terra ...Nova Bay (TBN) polynya to the eastern edge of the Ross Ice Shelf (RIS). We analyzed picoplankton, nanoplankton and microplankton fractions, with particular regard to heterotrophy versus autotrophy and the size-based partitioning of living carbon. Plankton dynamics were closely associated with hydrological features: (1) diatom blooms were confined to the ice-edge TNB polynya, (2)
Phaeocystis dominance was confined to the lower salinity surface waters, diluted by the RIS and the Drygalsky Ice Tongue, (3) heterotrophic communities prevailed in the warmer surface waters of the Drygalsky basin, where most of the living carbon was associated with tintinnids (namely
Codonellopsis gaussi).
Phaeocystis distribution suggested that low salinities may be the main driving force in enhancing their development. In the deepest layers, heterotrophic communities were dominated by bacteria. Along the transect, we did not find evidence of any unique and continuous temporal evolution of the ice melting process, freshening of the water, and warming of the surface layer that trigger summer algal blooms and plankton dynamics. The physical features, which, in turn, mainly depend on the past history of ice retreating, seem to control the development of the planktonic system which showed a patchy distribution, shifting from an autotrophic community of the ice-edge area (TNB polynya) to a heterotrophic community of the warmer surface layer in the Drygalsky basin, which was ice-free for a longer period before the sampling.
A direct, microscopic fluorescent antibody method was developed to detect the occurrence of
Enterococcus faecium in coastal aquatic environments and was compared with the conventional membrane ...filtering method. The “
in situ” application of the antibody-based protocol in the analysis of water samples collected from coastal polyhaline habitats demonstrated good sensitivity and ease of implementation. Data obtained with the microscopic technique were in agreement with those obtained from culture counts. The fluorescent antibody method proved to be a rapid and reliable technique for the detection of
E. faecium. The advantages and limitations intrinsic to the method are discussed, highlighting the potential of this new technique for monitoring coastal aquatic environments.
The Mediterranean Sea is an enclosed basin composed of two similar basins and different sub-basins. It is a concentration basin, where evaporation exceeds precipitation. In the surface layer there is ...an inflow of Atlantic water which is modified along its path to the Eastern basin. This transformation occurs through surface heat loss and evaporation specifically in the Levantine basin. The Mediterranean is furthermore the site of water mass formation processes, which can be studied experimentally because of their easy accessibility. There are two main reasons why the Mediterranean is important. The first one is the impact of the Mediterranean on the global thermohaline circulation, the second reason is that the Mediterranean basin can be considered as Laborartory for investigating processes occurring on the global scale of the world ocean. In this paper authors want to provide a short historical review of the evolving knowledge of the Mediterranean circulation that has emerged from experimental investigations over the last decades. Authors start by describing the old picture of the basin circulation which had stationary, smooth large scale patterns. Then authors show the major experiments that led to the discovery of the sub-basin scale circulation and its mesoscale features. Authors conclude with the dynamical discovery of EMT in the 1990s and the most exciting ongoing new research programmes.
The study of plant-bound nutrient transport has been largely neglected in estuaries. Lately however, it has been shown that nutrients bound to macroalgae and seagrasses can constitute a major part of ...the nutrient transport in shallow tidal estuaries. Organic detritus in estuaries comes from various sources. This paper looks into the source of detritus from sloughing, and the transport behaviour of plant detritus under unidirectional flows. In order to determine the extent of the sloughing of macrophytes, the threshold current velocities for the traction and resuspension of the most common submersed macrophytes in Venice Lagoon (
Ulva lactuca,
Enteromorpha sp.,
Ceramium rubrum,
Cladophora sp., and
Chaetomorpha linum) were studied in a laboratory flume. It was found that all macrophytes subjected to flows of 1.5–3.0
cm
s
−1 move initially as bed load. The threshold for suspension of the macrophyte tissue was at current speeds >3
cm
s
−1. The exception was the filamentous macroalgae,
C. linum, which moved as bed load at all current speeds. This implies that the advection of plant-bound nutrients in Venice Lagoon is widespread and takes place over virtually all stages of the tide.
Initial experiments were carried out on unattached macroalgae. A second study focused on the sloughing of attached macroalgae by steady currents. The threshold current speeds at which sloughing commenced varied between different types of algae, and sloughing rate was related largely to current speed. The resuspension rates were uniform between the different macrophyte groups.
Our results help explain why plant matter has been trapped in nets close to the bed of Venice Lagoon on ebbing tides. It shows that a major component of the bedload is organic in origin. The results verify that a large proportion of the net nutrient export from estuaries is bound in macrophyte tissue. These findings need to be included in future ecological models that describe the resuspension, sloughing and settling of macrophytes.
OBJECTIVES: Drug utilization studies (DUS) are increasingly requested by regulatory authorities and payers to evaluate the benefit-risk of drugs in real-life. DUS usually aim at evaluating ...prescribing practices, including off-label use or contraindications, quantitatively or qualitatively against recommendations. Currently, most DUS involve clinical chart review, sometimes supplemented by interviews with patients or prescribers. Ethical requirements for these studies appear heterogeneous across countries and settings. The present study aims at defining the ethical and/or legal framework applicable for the conduct of DUS in hospital and ambulatory care settings in selected Latin American countries. METHODS: Two complementary strategies were used: (i) a review of existing legislative sources in selected Latin American countries and, (ii) a survey submitted to ethics committees and/or key informants which included case studies corresponding to different data collection methods, study populations and health care settings. RESULTS: The literature review confirmed the great disparity across local legislations on DUS in Latin America. In most countries, national regulations or guidelines are in existence but requirements differ from one country to another. In addition, ethical requirements at the level of institutions are also heterogeneous. Survey revealed that a site-specific ethics approval is commonly required for DUS involving ad hoc data collection and that data protection legislation varies between countries. For example, in Brazil, it appears that no specific regulation applies to observational studies including DUS whereas in Argentina, patient informed consent might be required for reviewing medical charts. Based on information collected, most ethics committees refer to the Declaration of Helsinki regarding requirements applicable for DUS. Complete results with details per country will be presented at ISPOR. CONCLUSIONS: Preliminary results suggest lack of consensus in the legislative and ethical framework for DUS across different Latin American countries. Such heterogeneity therefore leads to operational challenges for the implementation of cross-national studies.
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