A soluble domain of the membrane-anchoring chain of influenza virus hemagglutinin (HA2) folds in Escherichia coli into the low-pH-induced conformation.

The extensive refolding of the membrane-anchoring chain of hemagglutinin (HA) of influenza virus (termed HA2) in cellular endosomes, which initiates viral entry by membrane fusion, suggests that viral HA is meta-stable. HA2 polypeptide residues 38-175 expressed in Escherichia coli are reported here to fold in vivo into a soluble trimer. The structure appears to be the same as the low-pH-induced conformation of viral HA2 by alpha-helical content, thermodynamic stability, protease dissection, electron microscopy, and antibody binding. These results provide evidence that the structure of the low-pH-induced fold of viral HA2 (TBHA2) observed crystallographically is the lowest-energy-state fold of the HA2 polypeptide. They indicate that the HA2 conformation in viral HA before low pH activation of its fusion potential is metastable and suggest that removal of the receptor-binding chain (HA1) is enough to allow HA2 to adopt the stable state. Further, they provide direct evidence that low pH is not required to form the membrane-fusion conformation but acts to make this state kinetically accessible in viral HA.

Presynaptic Anchoring of PKA by AKAP7 is Required for Pattern Separation by Dentate Gyrus

Thesis (Ph.D.)--University of Washington, 2016-06

Anchoring effects in the development of false childhood memories

When people receive descriptions or doctored photos of events that never happened, they often come to remember those events. But if people receive both a description and a doctored photo, does the order in which they receive the information matter? We asked people to consider a description and a doctored photograph of a childhood hot air balloon ride, and we varied which medium they saw first. People who saw a description first reported more false images and memories than did people who saw a photo first, a result that fits with an anchoring account of false childhood memories. © 2010 The Psychonomic Society, Inc.

Electropermanent magnetic anchoring for surgery and endoscopy

The use of magnets for anchoring of instrumentation in minimally invasive surgery and endoscopy has become of increased interest in recent years. Permanent magnets have significant advantages over electromagnets for these applications; larger anchoring and retraction force for comparable size and volume without the need for any external power supply. However, permanent magnets represent a potential hazard in the operating field where inadvertent attraction to surgical instrumentation is often undesirable. The current work proposes an interesting hybrid approach which marries the high forces of permanent magnets with the control of electromagnetic technology including the ability to turn the magnet OFF when necessary. This is achieved through the use of an electropermanent magnet, which is designed for surgical retraction across the abdominal and gastric walls. Our electropermanent magnet, which is hand-held and does not require continuous power, is designed with a center lumen which may be used for trocar or needle insertion. The device in this application has been demonstrated successfully in the porcine model where coupling between an intraluminal ring magnet and our electropermanent magnet facilitated guided insertion of an 18 Fr Tuohy needle for guidewire placement. Subsequent investigations have demonstrated the ability to control the coupling distance of the system alleviating shortcomings with current methods of magnetic coupling due to variation in transabdominal wall thicknesses. With further refinement, the magnet may find application in the anchoring of endoscopic and surgical instrumentation for minimally invasive interventions in the gastrointestinal tract.

D3M: multicast listener mobility support mechanisms over distributed mobility anchoring architectures

The explosion in mobile data traffic is a driver for future network operator technologies, given its large potential to affect both network performance and generated revenue. The concept of distributed mobility management (DMM) has emerged in order to overcome efficiency-wise limitations in centralized mobility approaches, proposing not only the distribution of anchoring functions but also dynamic mobility activation sensitive to the applications needs. Nevertheless, there is not an acceptable solution for IP multicast in DMM environments, as the first proposals based on MLD Proxy are prone to tunnel replication problem or service disruption. We propose the application of PIM-SM in mobility entities as an alternative solution for multicast support in DMM, and introduce an architecture enabling mobile multicast listeners support over distributed anchoring frameworks in a network-efficient way. The architecture aims at providing operators with flexible options to provide multicast mobility, supporting three modes: the first one introduces basic IP multicast support in DMM; the second improves subscription time through extensions to the mobility protocol, obliterating the dependence on MLD protocol; and the third enables fast listener mobility by avoiding potentially slow multicast tree convergence latency in larger infrastructures, by benefiting from mobility tunnels. The different modes were evaluated by mathematical analysis regarding disruption time and packet loss during handoff against several parameters, total and tunneling packet delivery cost, and regarding packet and signaling overhead.

The politics of media policy [Review]

"The Politics of Media Policy opens with a highly insightful analysis of how to do media policy studies in original and significant ways. Unfortunately, by anchoring its empirical analysis closely to a desire to expose the hidden machinations of neo-liberal ideology, it loses focus the more that it moves out of the dominant terrain of political economy in the study of media ownership. Des Freedman has pointed to important new directions in media policy studies, but has unfortunately only got half way to developing a new synthesis for understanding the relationship between policy institutions and broader ideas." -- from author's personal website

The spermostatic and microbicidal actions of quinones and malemides : towards a dual-purpose contraceptive agent

There is an urgent need to develop safe, effective, dual-purpose contraceptive agents that combine the prevention of pregnancy with protection against sexually transmitted diseases. Here we report the identification of a group of compounds that on contact with human spermatozoa induce a state of “spermostasis,” characterized by the extremely rapid inhibition of sperm movement without compromising cell viability. These spermostatic agents were more active and significantly less toxic than the reagent in current clinical use, nonoxynol 9, giving therapeutic indices (ratio of spermostatic to cytotoxic activity) that were orders of magnitude greater than this traditional spermicide. Although certain compounds could trigger reactive oxygen species generation by spermatozoa, this activity was not correlated with spermostasis. Rather, the latter was associated with alkylation of two major sperm tail proteins that were identified as A Kinase-Anchoring Proteins (AKAP3 and AKAP4) by mass spectrometry. As a consequence of disrupted AKAP function, the abilities of cAMP to drive protein kinase A-dependent activities in the sperm tail, such as the activation of SRC and the consequent stimulation of tyrosine phosphorylation, were suppressed. Furthermore, analysis of microbicidal activity using Chlamydia muridarum revealed powerful inhibitory effects at the same low micromolar doses that suppressed sperm movement. In this case, the microbicidal action was associated with alkylation of Major Outer Membrane Protein (MOMP), a major chlamydial membrane protein. Taken together, these results have identified for the first time a novel set of cellular targets and chemical principles capable of providing simultaneous defense against both fertility and the spread of sexually transmitted disease.

Imagining neighbourhood-based community : an autoethnography

This research is an autoethnographic investigation of consumption experiences, public and quasi-public spaces, and their relationship to community within an inner city neighbourhood. The research specifically focuses on the gentrifying inner city, where class-based processes of change can have implications for people’s abilities to remain within, or feel connected to place. However, the thesis draws on broader theories of the throwntogetherness of the contemporary city (e.g., Amin and Thrift, 2002; Massey 2005) to argue that the city is a space where place-based meanings cannot be seen to be fixed, and are instead better understood as events of place – based on ever shifting interrelations between the trajectories of people and things. This perspective argues the experience of belonging to community is not just born of a social encounter, but also draws on the physical and symbolic elements of the context in which it is situated. The thesis particularly explores the ways people construct identifications within this shifting urban environment. As such, consumption practices and spaces offer one important lens through which to explore the interplay of the physical, social and symbolic. Consumer research tells us that consumption practices can facilitate experiences in which identity-defining meaning can be generated and shared. Consumption spaces can also support different kinds of collective identification – as anchoring realms for specific cultural groups or exposure realms that enable individuals to share in the identification practices of others with limited risk (Aubert-Gamet & Cova, 1999). Furthermore, the consumption-based lifestyles that gentrifying inner city neighbourhoods both support and encourage can also mean that consumption practices may be a key reason that people are moving through public space. That is, consumption practices and spaces may provide a purpose for which – and spatial frame against which – our everyday interactions and connections with people and objects are undertaken within such neighbourhoods. The purpose of this investigation then was to delve into the subjectivities at the heart of identifying with places, using the lens of our consumption-based experiences within them. The enquiry describes individual and collective identifications and emotional connections, and explores how these arise within and through our experiences within public and quasi-public spaces. It then theorises these ‘imaginings’ as representative of an experience of community. To do so, it draws on theories of imagination and its relation to community. Theories of imagined community remind us that both the values and identities of community are held together by projections that create relational links out of objects and shared practices (e.g., Benedict Anderson, 2006; Urry, 2000). Drawing on broader theories of the processes of the imagination, this thesis suggests that an interplay between reflexivity and fantasy – which are products of the critical and the fascinated consciousness – plays a role in this imagining of community (e.g., Brann, 1991; Ricoeur, 1994). This thesis therefore seeks to explore how these processes of imagining are implicated within the construction of an experience of belonging to neighbourhood-based community through consumption practices and the public and quasi-public spaces that frame them. The key question of this thesis is how do an individual’s consumption practices work to construct an imagined presence of neighbourhood-based community? Given the focus on public and quasi-public spaces and our experiences within them, the research also asked how do experiences in the public and quasi-public spaces that frame these practices contribute to the construction of this imagined presence? This investigation of imagining community through consumption practices is based on my own experiences of moving to, and attempting to construct community connections within, an inner city neighbourhood in Melbourne, Australia. To do so, I adopted autoethnographic methodology. This is because autoethnography provides the methodological tools through which one can explore and make visible the subjectivities inherent within the lived experiences of interest to the thesis (Ellis, 2004). I describe imagining community through consumption as an extension of a placebased self. This self is manifest through personal identification in consumption spaces that operate as anchoring realms for specific cultural groups, as well as through a broader imagining of spaces, people, and practices as connected through experiences within realms of exposure. However, this is a process that oscillates through cycles of identification; these anchor one within place personally, but also disrupt those attachments. This instability can force one to question the orientation and motives of these imaginings, and reframe them according to different spaces and reference groups in ways that can also work to construct a more anonymous and, conversely, more achievable collective identification. All the while, the ‘I’ at the heart of this identification is in an ongoing process of negotiation, and similarly, the imagined community is never complete. That is, imagining community is a negotiation, with people and spaces – but mostly with the different identifications of the self. This thesis has been undertaken by publication, and thus the process of imagining community is explored and described through four papers. Of these, the first two focus on specific types of consumption spaces – a bar and a shopping centre – and consider the ways that anchoring and exposure within these spaces support the process of imagining community. The third paper examines the ways that the public and quasi-public spaces that make up the broader neighbourhood context are themselves throwntogether as a realm of exposure, and considers the ways this shapes my imaginings of this neighbourhood as community. The final paper develops a theory of imagined community, as a process of comparison and contrast with imagined others, to provide a summative conceptualisation of the first three papers. The first paper, chapter five, explores this process of comparison and contrast in relation to authenticity, which in itself is a subjective assessment of identity. This chapter was written as a direct response to the recent work of Zukin (2010), and draws on theories of authenticity as applied to personal and collective identification practices by consumer researchers Arnould and Price (2000). In this chapter, I describe how my assessments of the authenticity of my anchoring experiences within one specific consumption space, a neighbourhood bar, are evaluated in comparison to my observations of and affective reactions to the social practices of another group of residents in a different consumption space, the local shopping centre. Chapter five also provides an overview of the key sites and experiences that are considered in more detail in the following two chapters. In chapter six, I again draw on my experiences within the bar introduced in chapter five, this time to explore the process of developing a regular identity within a specific consumption space. Addressing the popular theory of the cafe or bar as third place (Oldenburg, 1999), this paper considers the purpose of developing anchored relationships with people within specific consumption spaces, and explores the different ways this may be achieved in an urban context where the mobilities and lifestyle practices of residents complicate the idea of a consumption space as an anchoring or third place. In doing so, this chapter also considers the manner in which this type of regular identification may be seen to be the beginning of the process of imagining community. In chapter seven, I consider the ways the broader public spaces of the neighbourhood work cumulatively to expose different aspects of its identity by following my everyday movements through the neighbourhood’s shopping centre and main street. Drawing on the theories of Urry (2000), Massey (2005), and Amin (2007, 2008), this chapter describes how these spaces operate as exposure realms, enabling the expression of different senses of the neighbourhood’s spaces, times, cultures, and identities through their physical, social, and symbolic elements. Yet they also enable them to be united: through habitual pathways, group practices of appropriation of space, and memory traces that construct connections between objects and experiences. This chapter describes this as a process of exposure to these different elements. Our imagination begins to expand the scope of the frames onto which it projects an imagined presence; it searches for patterns within the physical, social, and symbolic environment and draws connections between people and practices across spaces. As the final paper, chapter eight, deduces, it is in making these connections that one constructs the objects and shared practices of imagined community. This chapter describes this as an imagining of neighbourhood as a place-based extension of the self, and then explores the ways in which I drew on physical, social, and symbolic elements in an attempt to construct a fit between the neighbourhood’s offerings and my desires for place-based identity definition. This was as a cumulative but fragmented process, in which positive and negative experiences of interaction and identification with people and things were searched for their potential to operate as the objects and shared practices of imagined community. This chapter describes these connections as constructed through interplay between reflexivity and fantasy, as the imagination seeks balance between desires for experiences of belonging, and the complexities of constructing them within the throwntogether context of the contemporary city. The conclusion of the thesis describes the process of imagining community as a reflexive fantasy, that is, as a product of both the critical and fascinated consciousness (Ricoeur, 1994). It suggests that the fascinated consciousness imbues experiences with hope and desire, which the reflexive imagining can turn to disappointment and shame as it critically reflects on the reality of those fascinated projections. At the same time, the reflexive imagination also searches the practices of others for affirmation of those projections, effectively seeking to prove the reality of the fantasy of the imagined community.

Reconnecting theory and practice in a pluralistic organizing context : issues and Aristotelian considerations

The overall purpose of this paper is to contribute to the theory - practice gap debate in organization studies, especially in pluralistic contexts such as project organizing. We briefly outline some of the current debates, i.e. modernist and postmodernist proposals, and the prevalent dichotomous thinking stance assumptions to better move beyond it, anchoring our contribution in the Aristotelian ethical and practical philosophy. We introduce the current state of the debate, part of the broad question of “science that matters”, and the various discourses between practice and academia within social sciences and more specifically organizational studies. We briefly critically summarize some main features of the two main philosophical stances (modernism, postmodernism), before presenting some key aspects, for the purpose of this paper, of the Aristotelian pre-modern practical and ethical philosophy. Then, we build on the foundations above established, discussing propositions to reconnect theory and practice according the Aristotelian ethical and practical philosophy, and some key implications for research notably in the following areas: roles played by practitioners and scholars, emancipatory praxeological style of reasoning, for closing the “phronetic gap” and reconnecting means and ends, facts and values, relation between collective praxis, development of “good practice” (standards), ethics and politics. We conclude highlighting the role of the suggested shift to an Aristotelian emancipatory style of reasoning for reconciling theory and practice.

Hyperbranched polymer-gold nanoparticle assemblies : role of polymer architecture in hybrid assembly formation and SERS activity

Plasmonic gold nano-assemblies that self-assemble with the aid of linking molecules or polymers have the potential to yield controlled hierarchies of morphologies and consequently result in materials with tailored optical (e.g. localized surface plasmon resonances (LSPR)) and spectroscopic properties (e.g. surface enhanced Raman scattering (SERS)). Molecular linkers that are structurally well-defined are promising for forming hybrid nano-assemblies which are stable in aqueous solution and are increasingly finding application in nanomedicine. Despite much ongoing research in this field, the precise role of molecular linkers in governing the morphology and properties of the hybrid nano-assemblies remains unclear. Previously we have demonstrated that branched linkers, such as hyperbranched polymers, with specific anchoring end groups can be successfully employed to form assemblies of gold NPs demonstrating near-infrared SPRs and intense SERS scattering. We herein introduce a tailored polymer as a versatile molecular linker, capable of manipulating nano-assembly morphologies and hot-spot density. In addition, this report explores the role of the polymeric linker architecture, specifically the degree of branching of the tailored polymer in determining the formation, morphology and properties of the hybrid nano-assemblies. The degree of branching of the linker polymer, in addition to the concentration and number of anchoring groups, is observed to strongly influence the self-assembly process. The assembly morphology shifts primarily from 1D-like chains to 2D plates and finally to 3D-like globular structures, with increase in degree of branching. Insights have been gained into how the morphology influences the SERS performance of these nano-assemblies with respect to hot-spot density. These findings supplement the understanding of the morphology determining nano-assembly formation and pave the way for the possible application of these nano-assemblies as SERS bio-sensors for medical diagnostics.

Self assembly of plasmonic core-satellite nano-assemblies mediated by hyperbranched polymer linkers

The morphology of plasmonic nano-assemblies has a direct influence on optical properties, such as localised surface plasmon resonance (LSPR) and surface enhanced Raman scattering (SERS) intensity. Assemblies with core-satellite morphologies are of particular interest, because this morphology has a high density of hot-spots, while constraining the overall size. Herein, a simple method is reported for the self-assembly of gold NPs nano-assemblies with a core-satellite morphology, which was mediated by hyperbranched polymer (HBP) linkers. The HBP linkers have repeat units that do not interact strongly with gold NPs, but have multiple end-groups that specifically interact with the gold NPs and act as anchoring points resulting in nano-assemblies with a large (~48 nm) core surrounded by smaller (~15 nm) satellites. It was possible to control the number of satellites in an assembly which allowed optical parameters such as SPR maxima and the SERS intensity to be tuned. These results were found to be consistent with finite-difference time domain (FDTD) simulations. Furthermore, the multiplexing of the nano-assemblies with a series of Raman tag molecules was demonstrated, without an observable signal arising from the HBP linker after tagging. Such plasmonic nano-assemblies could potentially serve as efficient SERS based diagnostics or biomedical imaging agents in nanomedicine.

High-voltage insulation organic-inorganic nanocomposites by plasma polymerization

In organic-inorganic nanocomposites, interfacial regions are primarily influenced by the dispersion uniformity of nanoparticles and the strength of interfacial bonds between the nanoparticles and the polymer matrix. The insulating performance of organic-inorganic dielectric nanocomposites is highly influenced by the characteristics of interfacial regions. In this study, we prepare polyethylene oxide (PEO)-like functional layers on silica nanoparticles through plasma polymerization. Epoxy resin/silica nanocomposites are subsequently synthesized with these plasma-polymerized nanoparticles. It is found that plasma at a low power (i.e., 10 W) can significantly increase the concentration of C-O bonds on the surface of silica nanoparticles. This plasma polymerized thin layer can not only improve the dispersion uniformity by increasing the hydrophilicity of the nanoparticles, but also provide anchoring sites to enable the formation of covalent bonds between the organic and inorganic phases. Furthermore, electrical tests reveal improved electrical treeing resistance and decreased dielectric constant of the synthesized nanocomposites, while the dielectric loss of the nanocomposites remains unchanged as compared to the pure epoxy resin.

Centrobin regulates the assembly of functional mitotic spindles

The proper function of the spindle is crucial to the high fidelity of chromosome segregation and is indispensable for tumor suppression in humans. Centrobin is a recently identified centrosomal protein that has a role in stabilizing the microtubule structure. Here we functionally characterize the defects in centrosome integrity and spindle assembly in Centrobin-depleted cells. Centrobin-depleted cells show a range of spindle abnormalities including unfocused poles that are not associated with centrosomes, S-shaped spindles and mini spindles. These cells undergo mitotic arrest and subsequently often die by apoptosis, as determined by live cell imaging. Co-depletion of Mad2 relieves the mitotic arrest, indicating that cells arrest due to a failure to silence the spindle checkpoint in metaphase. Consistent with this, Centrobin-depleted metaphase cells stained positive for BubR1 and BubR1 S676. Staining with a panel of centrosome markers showed a loss of centrosome anchoring to the mitotic spindle. Furthermore, these cells show less cold-stable microtubules and a shorter distance between kinetochore pairs. These results show a requirement of Centrobin in maintaining centrosome integrity, which in turn promotes anchoring of mitotic spindle to the centrosomes. Furthermore, this anchoring is required for the stability of microtubule–kinetochore attachments and biogenesis of tension-ridden and properly functioning mitotic spindle.