6,253 research outputs found
Prediction of overwash in alongshore variable barrier islands [Previsão da ocorrência de galgamentos em ilhas barreira com variabilidade longilitoral]
Overwash prediction is very important for coastal zone
management. This work intends to identify alongshore variations in
storm impact and evaluate the role of sub-aerial and submerged
morphologies in overwash occurrence. For this study, 24 cross-shore
topo-bathymetric profiles were set on Barreta Island (Ria Formosa
barrier island system, Portugal). Pre- and post-overwash surveys were
made between August 2012 and April 2013. During overwash events,
tidal levels and wave parameters at breaking were obtained. Overwash
occurred under storm and non-storm conditions, the latter coincident
with spring high-tide. Beach morphology was spatially variable, and
changeable from one overwash episode to the next. Predictions of
overwash occurrence were made using the Overwash Potential, defined
as the difference between runup and barrier elevation. Several runup
equations were tested, and the results compared to the actual
observations. The selected predictor provided an accuracy of 88% for
the identification of the locations where overwash occurred. This study
proves that nearshore and foreshore morphologies have a major impact
on the longshore distribution of overwash.info:eu-repo/semantics/publishedVersio
Marine-friendly antifouling coating based on the use of a fatty acid derivative as a pigment
This study was devoted to examining the application of copper dodecanoate as a non-contaminant antifouling pigment due to its low copper content and fatty acid nature. For this purpose, antifouling paints with mono-component epoxy resin and rosin matrixes were formulated, and their antifouling efficiency was evaluated. Before its incorporation into the different formulations, the synthesized pigment was characterized. Immersion tests in a marine environment were carried out for 12 months to evaluate the antifouling efficiency of the developed paints; the results were compared with those from a commercial paint. The antifouling efficiency of the new epoxy formulation was found to be considerably higher than that of the rosin formulation and very similar to that of the commercial paint. Most importantly, the release of copper from the epoxy paint formulated with copper dodecanoate was 73.5% lower than that of the commercial paint, suggesting prolonged activity of the developed paint.Peer ReviewedPostprint (published version
Disorders of metal metabolism
Trace elements are chemical elements needed in minute amounts for normal physiology. Some of the physiologically relevant trace elements include iodine, copper, iron, manganese, zinc, selenium, cobalt and molybdenum. Of these, some are metals, and in particular, transition metals. The different electron shells of an atom carry different energy levels, with those closest to the nucleus being lowest in energy. The number of electrons in the outermost shell determines the reactivity of such an atom. The electron shells are divided in sub-shells, and in particular the third shell has s, p and d sub-shells. Transition metals are strictly defined as elements whose atom has an incomplete d sub-shell. This incomplete d sub-shell makes them prone to chemical reactions, particularly redox reactions. Transition metals of biologic importance include copper, iron, manganese, cobalt and molybdenum. Zinc is not a transition metal, since it has a complete d sub-shell. Selenium, on the other hand, is strictly speaking a nonmetal, although given its chemical properties between those of metals and nonmetals, it is sometimes considered a metalloid. In this review, we summarize the current knowledge on the inborn errors of metal and metalloid metabolism
Price-setting hotel competition with corporate social responsibility
Pricing plays an important role in any market competition, but particularly in those businesses that hold a seat in hyper
competitive economic activities such as hotels. This paper analyses a market competition between one corporate social
responsibility (CSR) hotel and one for profit (FP) hotel, in which both hotels set room prices. We study three different
market behaviors: (i) both hotels take their decisions simultaneously; (ii) the CSR hotel takes the leader position; (iii)
the FP hotel takes the leader position. For each situation, by using game theory techniques, we compute the different
outcomes of the model at equilibrium. We also describe the effects of CSR on the outcomes.info:eu-repo/semantics/publishedVersio
The Effect Of Type-III Antifreeze Proteins (AFPs) On CO2 Hydrate Slurry Formation
CO2 hydrate slurry is a favourable direct coolant of fresh products due to its large latent heat and phase change temperature around 5°C. Continuous production of this slurry is, however, difficult to realise due to the high rate of hydrate formation. The use of additives is proposed with the purpose of decreasing the formation rate so that the controllability of the process is improved. Type-III Antifreeze Proteins (AFPs) are non-poisonous additives which have proven to be inhibitors of hydrate formation. These additives have also shown to protect the bio-cells of fresh products from damaging by freezing. The effect of these additives on the CO2 hydrate formation rate is experimentally investigated. The experiments have been performed in a coil heat exchanger with 6 mm internal diameter under operating conditions corresponding to hydrate formation conditions. The concentration of Type-III AFPs has been varied: no additives, 5 ppm and 10 ppm. The mixture of additives and CO2-water solution is cooled down until the hydrate formation conditions are attained. The growth rate of hydrates on the wall of the heat exchanger has been derived from the variation of the overall heat transfer coefficient with time. Results show that the addition of AFPs changes the supersaturation degree of CO2 water solution needed to initiate the hydrate formation process. A low concentration of the proposed additives is sufficient to slow down the formation rate of CO2 hydrate improving significantly the controllability of the hydrate production process
Dynamic Scaling of Non-Euclidean Interfaces
The dynamic scaling of curved interfaces presents features that are
strikingly different from those of the planar ones. Spherical surfaces above
one dimension are flat because the noise is irrelevant in such cases. Kinetic
roughening is thus a one-dimensional phenomenon characterized by a marginal
logarithmic amplitude of the fluctuations. Models characterized by a planar
dynamical exponent , which include the most common stochastic growth
equations, suffer a loss of correlation along the interface, and their dynamics
reduce to that of the radial random deposition model in the long time limit.
The consequences in several applications are discussed, and we conclude that it
is necessary to reexamine some experimental results in which standard scaling
analysis was applied
Retrieval of nearshore bathymetry from Landsat 8 images: a tool for coastal monitoring in shallow waters
Nearshore bathymetry is likely to be the coastal variable that most limits the investigation of coastal processes
and the accuracy of numerical models in coastal areas, as acquiring medium spatial resolution data in the nearshore
is highly demanding and costly. As such, the ability to derive bathymetry using remote sensing techniques
is a topic of increasing interest in coastalmonitoring and research. This contribution focuses on the application of
the linear transform algorithm to obtain satellite-derived bathymetry (SDB) maps of the nearshore, at medium
resolution (30 m), from freely available and easily accessible Landsat 8 imagery. The algorithm was tuned with
available bathymetric Light Detection and Ranging (LiDAR) data for a 60-km-long nearshore stretch of a highly
complex coastal system that includes barrier islands, exposed sandy beaches, and tidal inlets (Ria Formosa,
Portugal). A comparison of the retrieved depths is presented, enabling the configuration of nearshore profiles
and extracted isobaths to be explored and compared with traditional topographic/bathymetric techniques
(e.g., high- and medium-resolution LiDAR data and survey-grade echo-sounding combined with high-precision
positioning systems). The results demonstrate that the linear algorithm is efficient for retrieving bathymetry
frommulti-spectral satellite data for shallowwater depths (0 to 12 m), showing amean bias of−0.2m, a median
difference of −0.1 m, and a root mean square error of 0.89 m. Accuracy is shown to be depth dependent, an
inherent limitation of passive optical detection systems. Accuracy further decreases in areas where turbidity is
likely to be higher, such as locations adjacent to tidal inlets. The SDB maps provide reliable estimations of the
shoreline position and of nearshore isobaths for different cases along the complex coastline analysed. The use
of freely available satellite imagery proved to be a quick and reliable method for acquiring updated mediumresolution,
high-frequency (days and weeks), low-cost bathymetric information for large areas and depths of
up to 12 m in clear waters without wave breaking, allowing almost constant monitoring of the submerged
beach and the shoreface.info:eu-repo/semantics/publishedVersio
A FLAMINGOS Deep Near Infrared Imaging Survey of the Rosette Complex I: Identification and Distribution of the Embedded Population
We present the results of a deep near-infrared imaging survey of the Rosette
Complex. We studied the distribution of young embedded sources using a
variation of the Nearest Neighbor Method applied to a carefully selected sample
of near-infrared excess (NIRX) stars which trace the latest episode of star
formation in the complex. Our analysis confirmed the existence of seven
clusters previously detected in the molecular cloud, and identified four more
clusters across the complex. We determined that 60% of the young stars in the
complex and 86% of the stars within the molecular cloud are contained in
clusters, implying that the majority of stars in the Rosette formed in embedded
clusters. We compare the sizes, infrared excess fractions and average
extinction towards individual clusters to investigate their early evolution and
expansion. We found that the average infrared excess fraction of clusters
increases as a function of distance from NGC 2244, implying a temporal sequence
of star formation across the complex. This sequence appears to be primordial,
possibly resulting from the formation and evolution of the molecular cloud and
not from the interaction with the HII region.Comment: Accepted by Astrophysical Journa
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