Shell Research Papers - Academia.edu (original) (raw)

The loss of Pb from snail soft tissues may depend on the excretion of Ca, and involve the mobilization of shell Ca. Most sub-adults in three populations of Cantareus aspersus (syn. Cornu aspersum Müller) either failed to add, or lost,... more

The loss of Pb from snail soft tissues may depend on the excretion of Ca, and involve the mobilization of shell Ca. Most sub-adults in three populations of Cantareus aspersus (syn. Cornu aspersum Müller) either failed to add, or lost, shell mass on a diet with 250 μg g−1 Pb. Their failure to mineralize shell extensions occurred irrespective of food consumed, time or dietary Mg. Budgets of metals for 36 individuals in each of two populations showed that Ca loss would account for the reduction in shell mass. Lead concentrations were higher in the reduced shells but this may be a consequence of their smaller mass, rather than its cause. In both populations shell reduction correlated with the total mass of Pb assimilated. Any shell growth may have been dependent on the initial Ca reserve in each snail. Differential movement of Mg, Pb and Ca occurred between the shell and soft tissues.► Differential movement of Pb, Ca and Mg occurs in the shells of C. aspersus. ► Mg does not affect Pb assimilation but shell Mg and Pb rise on a Pb-dosed diet. ► Ca is lost from the shell in most snails, and correlates with total Pb assimilation. ► Large initial shell Ca enables some snails to grow shell over 64 days on the diet. ► Uptake and toxic response to Pb appears linked to the Ca dynamics of the snails.

Outsourcing is a well debated phenomenon and it seems like many have the opinion if the firms shall be successful, it has to follow the trend of outsourcing. Outsourcing is something most industries practice, and certainly the petroleum... more

Outsourcing is a well debated phenomenon and it seems like many have the opinion if the firms shall be successful, it has to follow the trend of outsourcing. Outsourcing is something most industries practice, and certainly the petroleum industry. Outsourcing as part of a firm’s strategy seems to be highly established in the oil & gas industry. As the oil & gas industry established, it seems the frequency of outsourcing has matured along with it. The study evaluated the experiences that different oil and gas firms have had with outsourcing and also compared it with experiences from other industries. From the findings it is indicated that outsourcing in the oil and gas sector has been on the rise since early 1990’s. It is used as a formidable strategy to exert efficiency in operations and stay ahead of competition. The report concluded by asserting the importance of outsourcing as a prelude to higher performing enterprises in this sector. It recommends that the practice should be done within the acceptable frameworks such as allowing competitive bidding, outsourcing from credible providers, auditing the business processes, and benchmarking with other firms in the industry and beyond.

De geschiedenis van 1915 tot 2015 van de raffinaderij op Curaçao. Over de komst en opkomst, het vertrek van Shell, de band met Venezuela, de ontwikkeling onder PdVSA en de actuele milieudiscussie.

The logo is in charge of improving brand identity and creating brand awareness. There is no place on earth that the logo cannot reach; it touches people's lives. The power of the logos did not happen overnight, but in a long period of... more

The logo is in charge of improving brand identity and creating brand awareness. There is no place on earth that the logo cannot reach; it touches people's lives. The power of the logos did not happen overnight, but in a long period of time. Success of logo is not only depended on its design but marketing strategies, product quality, delivery network, consumer satisfaction, advertising investments, emotional and rational benefits. Corporate ID is the most significant part of a brand. There are certain amounts of components of the corporate ID kit however the most important one is the logo. It is the memorable face of a company, which communicates with the public. Consumers recognize brands via their logos. Also, firms introduce themselves to the world by their logos. Accordingly, the logo is the most central part of a firm, providing its communication and reflecting characteristics of the firm. This study is a conceptual research which is explained with three famous logo design and literature review method is used. From past to present, changing and renewing of the different logo faces are the mean objective of this study. The evolution of successful logos will be examined over selected examples. The best-known and worldwide famous logos: Apple Inc., Shell and Coca Cola are the sample group of this study. These companies also derive the strength of their logos from other successful operations carried out by the organization, such as marketing, logistics, reputation management, quality policies, and customer satisfaction. Logo stories

We present in this paper recent achievements realised on the application of strain smoothing in finite elements and propose suitable extensions to problems with discontinuities and singularities. The numerical results indicate that for 2D... more

We present in this paper recent achievements realised on the application of strain smoothing in finite elements and propose suitable extensions to problems with discontinuities and singularities. The numerical results indicate that for 2D and 3D continuum, locking can be avoided. New plate and shell formulations that avoid both shear and membrane locking are also briefly reviewed. The principle is then extended to partition of unity enrichment to simplify numerical integration of discontinuous approximations in the extended finite element method. Examples are presented to test the new elements for problems involving cracks in linear elastic continua and cracked plates. In the latter case, the proposed formulation suppresses locking and yields elements which behave very well, even in the thin plate limit. Two important features of the set of elements presented are their insensitivity to mesh distortion and a lower computational cost than standard finite elements for the same accuracy. These elements are easily implemented in existing codes since they only require the modification of the discretized gradient operator, B.

This article explores the relationship between the oil industry’s representation of operating conditions in key sites of extraction and the constitution of oil futures markets. An analysis of Shell Oil’s recent Scenarios publications, the... more

This article explores the relationship between the oil industry’s representation of operating conditions in key sites of extraction and the constitution of oil futures markets. An analysis of Shell Oil’s recent Scenarios publications, the ‘Trilemma Scenarios to 2025’ and subsequent ‘Scramble and Blueprints Scenarios to 2050’, provides insight into both the (global) social construction of oil prices and the oil industry’s reaction to social resistance in its operating environment – whether in the form of movements for resource sovereignty or climate change activism. Examining the implications of these two Scenario publications for key sites of Shell investment, the Nigerian Niger Delta and the Canadian Tar Sands, the article demonstrates that understanding the discursive implications of ‘peak oil’ for the petroleum industry requires contextualizing discussions of ‘scarcity’ within business agents role in shaping oil futures markets, and private industry’s interest in the ongoing development of unconventional fossil fuel sources. While the role of deregulated futures trading receives little attention in the Shell Scenarios, speculative trading – and thus perception concerning supply among business agents – is central to shaping global oil prices and thus the social conditions of the oil market.

A meshfree method for thin shells with finite strains and arbitrary evolving cracks is described. The C1 displacement continuity requirement is met by the approximation, so no special treatments for fulfilling the Kirchhoff condition are... more

A meshfree method for thin shells with finite strains and arbitrary evolving cracks is described. The C1 displacement continuity requirement is met by the approximation, so no special treatments for fulfilling the Kirchhoff condition are necessary. Membrane locking is eliminated by the use of a cubic or quartic polynomial basis. The shell is tested for several elastic and elasto-plastic examples and shows good results. The shell is subsequently extended to modelling cracks. Since no discretization of the director field is needed, the incorporation of discontinuities is easy to implement and straightforward. Copyright © 2007 John Wiley & Sons, Ltd.

To infer the early evolution of mollusc shell microstructures we must know the most ancient fossil record of molluscs. Fortunately the shells of many early molluscs are preserved via internal coatings and replacements by apatite that... more

To infer the early evolution of mollusc shell microstructures we must know the most
ancient fossil record of molluscs. Fortunately the shells of many early molluscs are preserved via
internal coatings and replacements by apatite that record sub-micrometer structural details that
otherwise would be lost during diagenetic recrystallization. We herein discuss the methodology by
which one can infer original shell microstructure from phosphatized fossils, pointing out the main
problems and solutions in interpreting these traces of original shell crystal morphology. We also
review the information these fossils have provided about the earliest evolution of the mollusc shell.
Our long-term goal is to create a dataset of microstructures in early molluscs, which will be useful
in understanding the incipient evolutionary arms race between molluscs and their predators, and
will help elucidate how the mollusc biomineralization toolkit was built through time.

La provincia de Mendoza tiene una historia petrolera de más de 120 años en toda su cadena de valor. Sin embargo, esta larga experiencia no ha sido en su mayoría estudiada y por ende el objetivo principal de este trabajo es analizar un... more

La provincia de Mendoza tiene una historia petrolera de más de 120 años en toda su cadena de valor. Sin embargo, esta larga experiencia no ha sido en su mayoría estudiada y por ende el objetivo principal de este trabajo es analizar un aspecto de esa historia: los primeros pasos en la destilación del petróleo y la comercialización de la nafta durante la década de 1920. Para ello mostraremos las actividades privadas llevadas a cabo por incipientes empresarios que buscaban insertarse en un mundo económico dominado por la producción vitivinícola. Específicamente, cómo se daba la venta de combustibles, la regulación del Estado y la concentración del mercado por las grandes empresas petroleras

Oyster shell is a crucial component of healthy oyster reefs. Shell planting has been a main component of oyster restoration efforts in many habitats and has been carried out on scales from individual and grass root efforts to multiagency... more

Oyster shell is a crucial component of healthy oyster reefs. Shell planting has been a main component of oyster restoration efforts in many habitats and has been carried out on scales from individual and grass root efforts to multiagency efforts across entire estuaries. However the cycling and lifetime of the shell that makes up the bulk of an oyster reef has only recently received attention, and most of the work to date has focused on the role of epi- and endobionts on shell degradation. Here we report findings from a laboratory study in which we manipulated pH in a flow-through control system using water from the mesohaline mouth of the Patuxent River to measure dissolution rates of intact oyster shell. Shells from the eastern oyster (Crassostrea virginica- Gmelin 1791) having three different legacies were exposed to four levels of pH that encompass a range typical of the mesohaline waters of Chesapeake Bay (~7.2 to 7.9 on the NBS scale). Mass loss over a two-week period was used to measure dissolution rate on three shell legacies: fresh, weathered, and dredged. We found that pH and shell legacy had significant effects on shell dissolution rate, with lower pH increasing dissolution rate. Fresh shell had the highest dissolution rate, followed by weathered then dredged shell. Dissolution rates were significantly different among all four pH treatments, except between the lowest (~7.2) and the next lowest (~7.4); however, shells lost mass even under non-corrosive conditions (~7.9). We discuss the implications of our findings to ongoing efforts to understand shell budgets and cycling in oyster reef habitat, the interaction of biological and geochemical agents of shell degradation, and the complexity associated with shell carbonate cycling in the unique milieu of the oyster reef.

The mortuary behavior of hunter-gatherers associated with a San Francisco Bay area shell mound is analyzed. Mortuary analyses in the region are reviewed and critiqued, highlighting the general difficulties associated with investigating... more

The mortuary behavior of hunter-gatherers associated with a San Francisco Bay area shell mound is analyzed. Mortuary analyses in the region are reviewed and critiqued, highlighting the general difficulties associated with investigating the mortuary behavior of hunter-gatherers. Using the concept of inequality and its link to surplus, a mortuary analysis of an example of a shell mound in the area, CA-ALA-328, is then conducted. A formal cemetery located beneath the shell mound is identified, followed by a burial setting involving inhumation into the matrix of the shell mound. A decrease in the level of inequality is observed in the burials as the site transitions from a cemetery to a shell mound. The implications of this change in inequality are explored, and a new interpretation of mortuary behavior at shell mounds is presented. Finally, several areas where the analysis contributes to the development of archaeological theory are outlined.

In this paper a study is presented on the experimental and numerical analysis of the failure process of mild steel sheets subjected to normal impact by hemispherical projectiles. The experiments have been performed using a direct impact... more

In this paper a study is presented on the experimental and numerical analysis of the failure process of mild steel sheets subjected to normal impact by hemispherical projectiles. The experiments have been performed using a direct impact technique based on Hopkinson tube as a force measurement device. The tests covered a wide range of impact velocities. Both lubricated and dry conditions between specimen and projectile have been applied. Different failure modes for each case were found. For lubricated conditions a petalling was observed, whereas for dry conditions a radial neck along with a hole enlargement reduces the formation of petalling. The perforation process has been simulated by the application of 3D analysis using ABAQUS/Explicit FE code. The material behavior of the circular specimen was approximated by three different constitutive relations. The main task was to study the influence of the material definition on the response of the sheet specimen with special attention to the failure mode.

Fachartikel: Globaler Wandel stellt Ölgesellschaften und andere multinationale Unternehmungen vor komplexe Entscheidungssituationen. Dieser Aufsatz zeigt am Beispiel Shell, welche Positionen die Firma bezüglich verschiedener Issues, wie... more

Fachartikel: Globaler Wandel stellt Ölgesellschaften und andere multinationale Unternehmungen vor komplexe Entscheidungssituationen. Dieser Aufsatz zeigt am Beispiel Shell, welche Positionen die Firma bezüglich verschiedener Issues, wie z.B. Brent Spar, vertrat und wie das Verhalten eines multinationalen Konzerns auf seinen Geschäftsprinzipien fussen soll.

Two hundred ninety beads have been found in an archaeological site located over a hill beside Cigüela river, tributary of Guadiana river. The place, in Arenas de San Juan (Ciudad Real), is called Los Parrales. Its significance is relevant... more

Two hundred ninety beads have been found in an archaeological site located over a hill beside Cigüela river, tributary of Guadiana river. The place, in Arenas de San Juan (Ciudad Real), is called Los Parrales. Its significance is relevant because of the high number of elements found together, associated with Bell Baker pottery and the discovery’s customs: not in an archaeological stratigraphy but in surface survey. Cultural contacts between people who lived in different sections of Guadiana river, confirmed in other prehistoric periods, can help to explain this find.

The paper addresses the problem of sandwich beams/panels with junctions between different core materials. The physics of the impairing local effects induced by a mismatch of the elastic material properties at core junctions is discussed,... more

The paper addresses the problem of sandwich beams/panels with junctions between different core materials. The physics of the impairing local effects induced by a mismatch of the elastic material properties at core junctions is discussed, and the results of an experimental investigation concerning the failure behaviour of sandwich beams with conventional butt and ‘structurally graded’ core junctions subjected to quasi-static as well as fatigue loading conditions in a three-point bending scheme are discussed. The novel concept of structurally graded core junctions presents different geometrical shapes of the core interfaces (e.g. bias junctions) as well as core junctions with locally reinforced faces. The novel design of core junctions is shown to provide larger quasi-static failure loads, and more beneficial crack initiation and propagation patterns in sandwich beams. Furthermore, it is shown that structurally graded core junctions perform much better than conventional butt junctions under fatigue conditions. Thus, the fatigue life of the sandwich beams with structurally graded core junctions was up to 38% higher than the fatigue life of the sandwich beams with the conventional junction design.