130,935 research outputs found
Iceberg Scour and Shell Damage in the Antarctic Bivalve Laternula elliptica
Get PDFWe document differences in shell damage and shell thickness in a bivalve mollusc (Laternula elliptica) from seven sites around Antarctica with differing exposures to ice movement. These range from 60% of the sea bed impacted by ice per year (Hangar Cove, Antarctic Peninsula) to those protected by virtually permanent sea ice cover (McMurdo Sound). Patterns of shell damage consistent with blunt force trauma were observed in populations where ice scour frequently occurs; damage repair frequencies and the thickness of shells correlated positively with the frequency of iceberg scour at the different sites with the highest repair rates and thicker shells at Hangar Cove (74.2% of animals damaged) compared to the other less impacted sites (less than 10% at McMurdo Sound). Genetic analysis of population structure using Amplified Fragment Length Polymorphisms (AFLPs) revealed no genetic differences between the two sites showing the greatest difference in shell morphology and repair rates. Taken together, our results suggest that L. elliptica exhibits considerable phenotypic plasticity in response to geographic variation in physical disturbance
Determination of K shell XRF parameters and K to L shell vacancy transfer probabilities of ferromagnetic 3d transition metals
No full textIn this study, K shell X-ray fluorescence cross-sections (sigma K alpha, sK beta and sigma K), K shell fluorescence yields (omega K) and K to L shell vacancy transfer probabilities (eta KL) of ferromagnetic 3d transition metals (Fe, Co, Ni) were investigated to understand how the relationship between ferromagnetism and these values changes with atomic number by using energy dispersive X-ray fluorescence (EDXRF) technique. The all obtained experimental and theoretical results were comparatively given as a function of the atomic number. It was clearly observed that all of the investigated parameters depend on the atomic number and the ferromagnetism state of the atom
Joshua Davis: Author of Spare Parts
Get PDFCitation: K-State First (2016). Joshua Davis: Author of Spare Parts [Flier]. Manhattan, Kansas: K-State First.Flyer advertising Joshua Davis's author talk at Kansas State University
A Unified Shell model for Buoyancy-Driven Turbulence
No full textWe construct a unified shell model for stably stratified and convective turbulence. Shell model simulation of stably stratified flow in turbulent regime exhibit Bolgiano-Obukhbov (BO) scaling in which the kinetic energy spectrum varies as . However, simulation of convective turbulence shows Kolmogorov's spectrum. These results are consistent with the direct numerical simulations of Kumar {\em et al.} [Phys. Rev. E {\bf 90}, 023016 (2014)]. We also observe a dual scaling ( and ) for a limited range of parameters in stably stratified flow
Computational morphogenesis of free form shells: Filter methods to create alternative solutions
Get PDFp. 536-547Actual trends in numerical shape optimal design of structures deal with handling of very
large dimensions of design space. The goal is to allowing as much design freedom as
possible while considerably reducing the modelling effort. As a consequence, several
technical problems have to be solved to get procedures which are robust, easy to use and which can handle many design parameters efficiently. The paper briefly discusses several of the most important aspects in this context and presents many illustrative examples which show typical applications for the design of light weight shell and membrane structures.Bletzinger, K.; Firi, M.; Linhard, J.; Wüchner, R. (2009). Computational morphogenesis of free form shells: Filter methods to create alternative solutions. Editorial Universitat Politècnica de València. https://riunet.upv.es/handle/10251/654
Application of the continuum shell finite element SHB8PS to sheet forming simulation using an extended large strain anisotropic elastic–plastic formulation
Get PDFhttp://link.springer.com/article/10.1007%2Fs00419-012-0620-xThis paper proposes an extension of the SHB8PS solid–shell finite element to large strain anisotropic elasto-plasticity, with application to several non-linear benchmark tests including sheet metal forming simulations. This hexahedral linear element has an arbitrary number of integration points distributed along a single line, defining the "thickness" direction; and to control the hourglass modes inherent to this reduced integration, a physical stabilization technique is used. In addition, the assumed strain method is adopted for the elimination of locking. The implementation of the element in Abaqus/Standard via the UEL user subroutine has been assessed through a variety of benchmark problems involving geometric non-linearities, anisotropic plasticity, large deformation and contact. Initially designed for the efficient simulation of elastic–plastic thin structures, the SHB8PS exhibits interesting potentialities for sheet metal forming applications – both in terms of efficiency and accuracy. The element shows good performance on the selected tests, including springback and earing predictions for Numisheet benchmark problems
Dynamic expression of ancient and novel molluscan shell genes during ecological transitions
Get PDFBackground: The Mollusca constitute one of the most morphologically and ecologically diverse metazoan phyla, occupying a wide range of marine, terrestrial and freshwater habitats. The evolutionary success of the molluscs can in part be attributed to the evolvability of the external shell. Typically, the shell first forms during embryonic and larval development, changing dramatically
in shape, colour and mineralogical composition as development and maturation proceeds. Major developmental transitions in shell morphology often correlate with ecological transitions (e.g. from a planktonic to benthic existence at metamorphosis). While the genes involved in molluscan biomineralisation are beginning to be identified, there is little understanding of how these are developmentally regulated, or if the same genes are operational at different stages of the mollusc's life.
Results: Here we relate the developmental expression of nine genes in the tissue responsible for shell production – the mantle – to ecological transitions that occur during the lifetime of the tropical abalone Haliotis asinina (Vetigastropoda). Four of these genes encode evolutionarily ancient proteins, while four others encode secreted proteins with little or no identity to known proteins.
Another gene has been previously described from the mantle of another haliotid vetigastropod. All nine genes display dynamic spatial and temporal expression profiles within the larval shell field and juvenile mantle.
Conclusion: These expression data reflect the regulatory complexity that underlies molluscan shell construction from larval stages to adulthood, and serves to highlight the different ecological demands placed on each stage. The use of both ancient and novel genes in all stages of shell
construction also suggest that a core set of shell-making genes was provided by a shared metazoan ancestor, which has been elaborated upon to produce the range of molluscan shell types we see today
Limit-point buckling analyses using solid, shell and solid–shell elements
Get PDFIn this paper, the recently-developed solid-shell element SHB8PS is used for the analysis of a representative set of popular limit-point buckling benchmark problems. For this purpose, the element has been implemented in Abaqus/Standard finite element software and the modified Riks method was employed as an efficient path-following strategy. For the. benchmark problems tested, the new element shows better performance compared to solid elements and often performs as well as state-of-the-art shell elements. In contrast to shell elements, it allows for the accurate prescription of boundary conditions as applied to the actual edges of the structure.Agence Nationale de la Recherche, France (ANR-005-RNMP-007
Steven Johnson Author Talk Poster
No full textK-State Book NetworkA poster advertising an author talk by Steven Johnson at Kansas State University on September 3, 2014. Steven Johnson's book "The Ghost Map" was the 2014-2015 common book
‘Shell to Sea’ in Ireland: building social movement potency
No full textIn 1996 the Corrib gas field, holding over 1 trillion cubic feet of gas, was discovered by Enterprise Oil 83km off the North West coast of Ireland. Acquired by Shell in 2002,
proposed extraction and processing is now a co-venture between several multinational energy corporations who aim to transport the gas some 90kms via pipeline to an onshore refinery site at Bellanaboy. Although heralded as a significant opportunity for development and employment by Shell and participating companies, local resistance to the proposals, on social and environmental grounds, has been
sustained and effective. Mirroring global conflicts between the petrochemical industry and local people and lifeworlds, this resistance has elicited repressive responses,
including the jailing of local landowners by the Irish state following their resistance to unprecedented compulsory land acquisition orders, and the taking out of a court injunction by Shell in 2005. Drawing on elements of contemporary social movement theory, and on both field research and analysis of campaign documents and media
reports, this paper seeks to describe and reflect on the shape and spread of the social movement that has arisen in response to this development project. We focus on the
‘Shell to Sea’ campaign which has argued for the offshore, as opposed to the onshore, development of the gas field, and has garnered support from many other social movement groups and networks. In particular we consider the use of alternative media in strengthening shared networks of concern and in engaging critically with corporate media representations of both the project and the mobilisation. We
conclude that social movement effectiveness and potency is in large part an outcome of collective and subjective commitments to intense work effort and the sharing of felt
solidarity regarding environmental and social concerns; and we iterate the significance of affective and subjective dimensions of social movement activities alongside more
conventional descriptions of work practices and structuring contexts
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