Evolution of a Holocene delta driven by episodic sediment delivery and coseismic deformation, Puget Sound, Washington, USA

This paper is not subject to U.S. copyright. The definitive version was published in Sedimentology 53 (2006): 1211-1228, doi:10.1111/j.1365-3091.2006.00809.x.Episodic, large-volume pulses of volcaniclastic sediment and coseismic subsidence of the coast have influenced the development of a late Holocene delta at southern Puget Sound. Multibeam bathymetry, ground-penetrating radar (GPR) and vibracores were used to investigate the morphologic and stratigraphic evolution of the Nisqually River delta. Two fluvial–deltaic facies are recognized on the basis of GPR data and sedimentary characteristics in cores, which suggest partial emplacement from sediment-rich floods that originated on Mount Rainier. Facies S consists of stacked, sheet-like deposits of andesitic sand up to 4 m thick that are continuous across the entire width of the delta. Flat-lying, highly reflective surfaces separate the sand sheets and comprise important facies boundaries. Beds of massive, pumice- and charcoal-rich sand overlie one of the buried surfaces. Organic-rich material from that surface, beneath the massive sand, yielded a radiocarbon age that is time-correlative with a series of known eruptive events that generated lahars in the upper Nisqually River valley. Facies CF consists of linear sandbodies or palaeochannels incised into facies S on the lower delta plain. Radiocarbon ages of wood fragments in the sandy channel-fill deposits also correlate in time to lahar deposits in upstream areas. Intrusive, sand-filled dikes and sills indicate liquefaction caused by post-depositional ground shaking related to earthquakes. Continued progradation of the delta into Puget Sound is currently balanced by tidal-current reworking, which redistributes sediment into large fields of ebb- and flood-oriented bedforms.This study was supported by the Coastal and Marine Geology Program, and the Earthquake Hazards Program of the U.S. Geological Survey

Deleuze-inspired action research in the university: Mobilising Deleuzian concepts to rethink research on the reflective writing practices of student teachers

This article offers an insight into the process and potential of Deleuze-inspired action research. It draws on a classroom action research (CAR) project that critically reconceptualises practices of reflective writing in teacher education, including the widespread use of the ‘professional learning journal’ as a resource to facilitate reflection on practice. Students following a teacher education programme in England took part in an innovative mode of engagement with texts, including their learning journals, drawing on the Deleuzo-Guattarian notion of the text as an agent that acts outside of itself. The process was called ‘implicated reading’. An example of a teaching and learning intervention, in the form of a seminar transcript, is offered as an illustration of how Deleuzian theory and philosophy can inspire and shape innovations in practice. The transcript also serves as an opportunity to reimagine the ways in which data and data analysis are conceptualised and practiced in action research (AR) projects. Data is (re)conceptualised as agentic, rather than inert or indifferent. Synthesis is privileged over analysis so that the transcript acts as a provocation to rethink the relation between theory and data, asking what is made possible when these are ‘plugged into’ one another to raise questions that otherwise would have remained unthought. Ultimately, the article offers a worked example of what happens when action researchers take up the challenge of working and thinking within a Deleuzian ontology that seeks to maintain the plurality and potentialities of AR in practice

Parallel Evolution and Coexpression of the Proteolipid Proteins and Protein Zero in Vertebrate Myelin

AbstractVertebrate myelin contains two proteins that mediate compaction: protein zero (P0), an immunoglobulin gene superfamily member, or proteolipid proteins, 4-hydrophobic domain–motif proteins biogenetically unrelated to P0. The prevailing view has been that expression of P0 and proteolipid proteins is mutually exclusive; P0, which mediates myelin compaction in fish, is thought to be completely replaced by the newer proteolipid proteins in the terrestrial vertebrate CNS. However, we now find that proteolipid proteins are actually major myelin constituents in bony fish and amphibia, and so are coexpressed with P0. Clearly, myelin proteolipids are not new additions to the myelin protein repertoire, but instead were ancestral sheath components, expressed ∼440 million years ago in the first myelinated fish that existed at least ∼100 million years before the origin of amphibians. In conclusion, P0 and the proteolipid proteins are evolving in parallel in myelinating cells of most vertebrate species

Rapid Conduction and the Evolution of Giant Axons and Myelinated Fibers

Nervous systems have evolved two basic mechanisms for increasing the conduction speed of the electrical impulse. The first is through axon gigantism: using axons several times larger in diameter than the norm for other large axons, as for example in the well-known case of the squid giant axon. The second is through encasing axons in helical or concentrically wrapped multilamellar sheets of insulating plasma membrane — the myelin sheath. Each mechanism, alone or in combination, is employed in nervous systems of many taxa, both vertebrate and invertebrate. Myelin is a unique way to increase conduction speeds along axons of relatively small caliber. It seems to have arisen independently in evolution several times in vertebrates, annelids and crustacea. Myelinated nerves, regardless of their source, have in common a multilamellar membrane wrapping, and long myelinated segments interspersed with ‘nodal’ loci where the myelin terminates and the nerve impulse propagates along the axon by ‘saltatory’ conduction. For all of the differences in detail among the morphologies and biochemistries of the sheath in the different myelinated animal classes, the function is remarkably universal