scholarly journals ASSESSMENT OF TIDE AND WIND EFFECTS ON THE HYDRODYNAMICS AND INTERACTIONS BETWEEN TIJUCAS BAY AND THE ADJACENT CONTINENTAL SHELF, SANTA CATARINA, BRAZIL

2014 ◽  
Vol 32 (3) ◽  
pp. 515
Author(s):  
Márcio Fabiano de Souza ◽  
Carlos Augusto França Schettini
Keyword(s):  
Continental Shelf ◽  
Residence Time ◽  
Wind Direction ◽  
River Discharge ◽  
Water Exchange ◽  
Coastal Processes ◽  
Input And Output ◽  
Continental Shelves ◽  
The Difference

ABSTRACT. The importance of understanding coastal processes and their relationships to continental shelves has become increasingly important as coastal areasexperience great socio-economic growth. In this context, Tijucas Bay and its interactions with the adjacent continental shelf was a subject of study through the use ofa numerical model (MOHID Water Modeling System) for analysis of its hydrodynamics, exchanges of water masses between the bay and the continental shelf and thewater’s residence time in the bay. Simulations were run for 30 or more days. Boundary conditions for the simulations were tides, constant river discharge (24 m3.s–1)and winds. Wind time series represented typical conditions in the region, with NE winds (3 m.s–1) forcing the domain for five days, then turning in the counterclockwisedirection for 12 hours until they were oriented in the SE direction (8 m.s–1), remaining two days in this direction and again turning counterclockwise for 12 hours andending in the NE direction. Three scenarios have been proposed for the experiment; scenario 1 was forced by tides and river discharge, and scenarios 2 and 3 wereforced by tides, river discharge and winds. The difference between scenarios 2 and 3 was the wind direction at the beginning of the simulations: scenario 2 began withNE winds, and scenario 3 began with SE winds. The results showed that the hydrodynamics and water exchange of Tijucas Bay were strongly influenced by tide andwind. The tide provided the input and output water pattern in the bay, while the wind accelerated the process, increasing the speed of exchange between the bay and theadjacent shelf. Superficial layers were the most affected by the winds. The easternmost portion of the bay exhibited the greatest current speeds, with a tendency to forma gyre current with water input at one end and output at the other, depending upon wind direction. In the shallower regions, currents exhibited their greatest speeds,while in the deeper areas, the inverse was found. The residence time for scenario 1 was 75 days, and for scenarios 2 and 3, the residence times were 19 and 15 days,respectively. The hydrodynamics of Tijucas Bay is a sum of processes related to its forcings; however, it is important to highlight the role of winds as one of the majordeterminants of the dynamics of this region, directly affecting transport throughout the bay.Keywords: circulation, estuary-shelf interaction, residence time. RESUMO. Atualmente o entendimento de processos costeiros e sua relação com a plataforma continental ganha importância a medida em que as regiões costeira tornam-se áreas de grande expansão sócio-econômica. Neste contexto, a Baía de Tijucas e sua interação com a plataforma adjacente foi alvo de investigação através do uso de modelo numérico (MOHID) para análise da hidrodinâmica, troca de massas de água entre baía e plataforma e tempo de residência da baía. As simulações correram por 30 dias ou mais. As condições de fronteiras para as simulações foram maré, descarga fluvial constante (24 m3.s–1) e ventos. As séries temporais deventos representam condições típicas da região com ventos NE (3 m.s–1) forçando o domínio por 5 dias girando no sentido anti-horário durante 12 horas até a direção SE (8 m.s–1), permanecendo por 2 dias nesta direção e novamente girando no sentido anti-horário por 12 horas até a direção NE. Três cenários foram propostos parao experimento, cenário 1 foi forçado por marés e descarga fluvial, cen´arios 2 e 3 forçados por marés, descarga fluvial e ventos. A diferenc¸a entre os cenários 2 e 3 é a direçãoo do vento no início das simulações, cenário 2 começa com vento NE e cenário 3 com vento SE. Os resultados mostram que a hidrodinâmica e a troca de água da Baía de Tijucas são fortemente influenciadas pela maré e pelo vento. A maré proporciona um padrão de entrada e saída de água da baía, enquanto o vento acelera oprocesso aumentando as velocidades de troca entre baía e plataforma adjacente. As camadas superficiais são mais afetadas pelos ventos. As extremidades da baía nasua porção mais a leste apresentam as maiores velocidades das correntes, a tendência é a formação de uma corrente em forma de giro com entrada de água por uma extremidade e saída por outra, dependendo da direção do vento. Nas partes mais rasas as correntes apresentam maiores velocidades enquanto nas partes mais profundas é o inverso. O tempo de residência para o cenário 1 foi de 75 dias, enquanto os cenários 2 e 3 apresentaram tempo de residência de 19 e 15 dias, respectivamente.A hidrodinâmica da Baía de Tijucas é um somatório de processos relacionados às suas forçantes. Entretanto ´e importante destacar o papel dos ventos como um dosprincipais condicionantes da dinâmica desta região afetando diretamente o transporte baía afora.Palavras-chave: circulação, interação estuário-plataforma, tempo de residência.

scholarly journals The role of continental shelves in nitrogen and carbon cycling

2010 ◽  
Vol 7 (1) ◽  
pp. 177-205
Author(s):  
K. Fennel
Keyword(s):  
Continental Shelf ◽  
North Atlantic ◽  
Deep Ocean ◽  
Open Ocean ◽  
Biogeochemical Models ◽  
Inorganic Matter ◽  
Continental Shelves ◽  
Shelf Region ◽  
Transformation Processes

Abstract. Continental shelves play a key role in the cycling of nitrogen and carbon. Here the physical transport and biogeochemical transformation processes affecting the fluxes into and out of continental shelf systems are reviewed, and their role in the global cycling of both elements is discussed. Uncertainties in observation-based estimates of nitrogen and carbon fluxes mostly result from uncertainties in the shelf-open ocean exchange of organic and inorganic matter, which is hard to quantify based on observations alone, but can be inferred from biogeochemical models. Model-based nitrogen and carbon budgets are presented for the Northwestern North Atlantic continental shelf. Results indicate that shelves are an important sink for fixed nitrogen and a source of alkalinity, but are not much more efficient in exporting organic carbon to the deep ocean than the adjacent open ocean for the shelf region considered.

scholarly journals The role of continental shelves in nitrogen and carbon cycling: Northwestern North Atlantic case study

Ocean Science ◽  
2010 ◽  
Vol 6 (2) ◽  
pp. 539-548 ◽  
Author(s):  
K. Fennel
Keyword(s):  
Continental Shelf ◽  
North Atlantic ◽  
Deep Ocean ◽  
Open Ocean ◽  
Biogeochemical Models ◽  
Inorganic Matter ◽  
Continental Shelves ◽  
Shelf Region

Abstract. Continental shelves play a key role in the cycling of nitrogen and carbon. Here the physical transport and biogeochemical transformation processes affecting the fluxes into and out of continental shelf systems are reviewed, and their role in the global cycling of both elements is discussed. Uncertainties in the magnitude of organic and inorganic matter exchange between shelves and the open ocean is a major source of uncertainty in observation-based estimates of nitrogen and carbon fluxes. The shelf-open ocean exchange is hard to quantify based on observations alone, but can be inferred from biogeochemical models. Model-based nitrogen and carbon budgets are presented for the Northwestern North Atlantic continental shelf. Results indicate that shelves are an important sink for fixed nitrogen and a source of alkalinity, but are not much more efficient in exporting organic carbon to the deep ocean than the adjacent open ocean for the shelf region considered.

scholarly journals Beyond residence time: quantifying factors that drive the spatially explicit filtration services of a “pristine” oyster population

2021 ◽  
Author(s):  
M.W. Gray ◽  
D. Pinton ◽  
A. Canestrelli ◽  
N. Dix ◽  
P. Marcum ◽  
...  
Keyword(s):  
Residence Time ◽  
Particle Concentration ◽  
Spatial Scales ◽  
Spatially Explicit ◽  
Physical Factors ◽  
Oyster Reefs ◽  
Oyster Population ◽  
Downstream Effects ◽  
The Difference

AbstractThe Guana-Tolomato-Matanzas (GTM) system is a relatively pristine and well-flushed estuary in Northeastern Florida, USA and characterized as having an extraordinarily high abundance of oysters. Historically, dense populations of oysters, such as those found in GTM, are believed to play an important role in water filtration; however, few biofiltration studies have had access to such pristine populations. To quantify the filtration service (FS) of Eastern oysters (Crassostrea virginica) in GTM at several spatial scales (i.e. reef, watershed, estuary), we implemented a model that solves for the hydrodynamics and depletion of particulate matter passing over model oyster populations, the latter of which were derived from detailed bay-wide surveys. The model results suggested that oyster reefs populating the GTM play an important role in water quality by filtering ~60% of the estuary’s volume within its residence time. Our approach teases apart the role of reef size, residence time, particle concentration, and other physical factors on the generation of FS at different spatial scales. Downstream effects were found to be very important for estuary FS, which depend on the spatial distribution of the reefs in the GTM and local and estuarine-scale hydrodynamics. Therefore, the difference between “realized” FS and the “potential” FS of a given reef may be substantial when considering the complex hydrodynamic and connectivity among populations at several scales. Our model results provide clear and actionable information for management of these oyster populations and conservation of their ecosystem services.

Part I Assessing the UN Institutional Structure for Global Ocean Governance: The UN’s Role in Global Ocean Governance, 4 The Role of the Commission on the Limits of the Continental Shelf in the Governance of the Seas and Oceans

2018 ◽  
Author(s):  
Subedi Surya P
Keyword(s):  
United Nations ◽  
Continental Shelf ◽  
Global Ocean ◽  
Financial Resources ◽  
Law Of The Sea ◽  
Ocean Governance ◽  
Continental Shelves ◽  
United Nations Convention ◽  
The Law

This chapter discusses the role of the Commission on the Limits of the Continental Shelf, established under the United Nations Convention on the Law of the Sea (UNCLOS), in the governance of the seas and oceans. It first considers the competition for the resources of the seas and oceans among States before providing an overview of the functions of the Commission. It then outlines the criteria for the establishment of the outer limits of the continental shelf and proceeds by analysing the challenges for the Commission in dealing with claims by coastal States for the extension of their continental shelves beyond 200 nautical miles. It also examines issues such as ambiguity in the law itself, the workload of the Commission, problems of enforcement, questions of transparency and accountability, financial resources, and independence of the Commissioners.

Osmoregulation in Australian Freshwater Mussels (Lamellibranchiata). I. Water and Chloride Ion Exchange in Hyridella australis (Lam.)

1953 ◽  
Vol 4 (2) ◽  
pp. 317 ◽  
Author(s):  
ID Hiscock
Keyword(s):  
Water Exchange ◽  
External Medium ◽  
Chloride Ion ◽  
Pericardial Fluid ◽  
The Body ◽  
Equilibrium Level ◽  
The Difference ◽  
Effective Seal ◽  
Australian Freshwater

The chlorinities of the blood and pericardial fluid of H. australis are similar, but always exceed those of the normal external medium. A study of blood chloride changes in mussels in media of different concentrations has shown that immediately following a change of medium there is a change in blood chlorinity, which tends to assume a new equilibrium level within 24 hr. The rapidity with which this change occurs depends upon the difference between the chlorinity of the blood and that of the external medium. A study of water exchange under identical conditions has shown that significant changes occur in the hydration of the mussel. In hypotonic media the mussel can regulate its water content; in hypertonic media it cannot, but its hydration assumes a new level within 24 hr. It is concluded that some part of the body surface is permeable to both salts and water. The urine of the mussel is hypotonic to the blood; it remains remarkably stabre in chlorinity despite changes in blood chlorinity. The role of the kidney as a regulating organ is discussed. The significance of shell movements in osmoregulation is demonstrated. Shell closure has been shown to be an effective seal from the external medium, allowing the mussel to resist desiccation.

The role of differential phase contrast in electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 176-177
Author(s):  
E.M. Waddell ◽  
J.N. Chapman ◽  
R.P. Ferrier
Keyword(s):  
Phase Contrast ◽  
Practical Method ◽  
Position Vector ◽  
Differential Phase ◽  
Pure Phase ◽  
Differential Phase Contrast ◽  
The Difference ◽  
Image Position ◽  
First Moment

Dekkers and de Lang (1977) have discussed a practical method of realising differential phase contrast in a STEM. The method involves taking the difference signal from two semi-circular detectors placed symmetrically about the optic axis and subtending the same angle (2α) at the specimen as that of the cone of illumination. Such a system, or an obvious generalisation of it, namely a quadrant detector, has the characteristic of responding to the gradient of the phase of the specimen transmittance. In this paper we shall compare the performance of this type of system with that of a first moment detector (Waddell et al.1977).For a first moment detector the response function R(k) is of the form R(k) = ck where c is a constant, k is a position vector in the detector plane and the vector nature of R(k)indicates that two signals are produced. This type of system would produce an image signal given bywhere the specimen transmittance is given by a (r) exp (iϕ (r), r is a position vector in object space, ro the position of the probe, ⊛ represents a convolution integral and it has been assumed that we have a coherent probe, with a complex disturbance of the form b(r-ro) exp (iζ (r-ro)). Thus the image signal for a pure phase object imaged in a STEM using a first moment detector is b2 ⊛ ▽ø. Note that this puts no restrictions on the magnitude of the variation of the phase function, but does assume an infinite detector.

On the Role of Transferrin in 67Ga Uptake by Tumor Cells

1988 ◽  
Vol 27 (04) ◽  
pp. 151-153
Author(s):  
P. Thouvenot ◽  
F. Brunotte ◽  
J. Robert ◽  
L. J. Anghileri
Keyword(s):  
Specific Binding ◽  
Subcellular Fractionation ◽  
Animal Blood ◽  
Tumor Bearing ◽  
Cell Structures ◽  
The Difference ◽  
Sarcoma Cells ◽  
In Vitro Uptake

In vitro uptake of 67Ga-citrate and 59Fe-citrate by DS sarcoma cells in the presence of tumor-bearing animal blood plasma showed a dramatic inhibition of both 67Ga and 59Fe uptakes: about ii/io of 67Ga and 1/5o of the 59Fe are taken up by the cells. Subcellular fractionation appears to indicate no specific binding to cell structures, and the difference of binding seems to be related to the transferrin chelation and transmembrane transport differences

REFLECTION COEFFICIENT OF AN ELECTROMAGNETIC WAVE IN CONDUCTIVE MEDIA

2018 ◽  
pp. 100-106
Author(s):  
M. S. Sudakova ◽  
M. L. Vladov ◽  
M. R. Sadurtdinov
Keyword(s):  
Reflection Coefficient ◽  
Ground Penetrating Radar ◽  
Electromagnetic Waves ◽  
Water Contamination ◽  
Survey Design ◽  
Direct And Inverse Problems ◽  
The Difference ◽  
Ground Penetrating ◽  
Ideal Dielectric

Within the ground penetrating radar bandwidth the medium is considered to be an ideal dielectric, which is not always true. Electromagnetic waves reflection coefficient conductivity dependence showed a significant role of the difference in conductivity in reflection strength. It was confirmed by physical modeling. Conductivity of geological media should be taken into account when solving direct and inverse problems, survey design planning, etc. Ground penetrating radar can be used to solve the problem of mapping of halocline or determine water contamination.

Speculative Realism and Science Fiction

2017 ◽  
Author(s):  
Brian Willems
Keyword(s):  
Science Fiction ◽  
Identity Formation ◽  
Cormac Mccarthy ◽  
Doris Lessing ◽  
Speculative Realism ◽  
Neil Gaiman ◽  
The World ◽  
The Difference ◽  
Quentin Meillassoux

A human-centred approach to the environment is leading to ecological collapse. One of the ways that speculative realism challenges anthropomorphism is by taking non-human things to be as valid objects of investivation as humans, allowing a more responsible and truthful view of the world to take place. Brian Willems uses a range of science fiction literature that questions anthropomorphism both to develop and challenge this philosophical position. He looks at how nonsense and sense exist together in science fiction, the way in which language is not a guarantee of personhood, the role of vision in relation to identity formation, the difference between metamorphosis and modulation, representations of non-human deaths and the function of plasticity within the Anthropocene. Willems considers the works of Cormac McCarthy, Paolo Bacigalupi, Neil Gaiman, China Miéville, Doris Lessing and Kim Stanley Robinson are considered alongside some of the main figures of speculative materialism including Graham Harman, Quentin Meillassoux and Jane Bennett.

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