Sampling Beyond Sound: Contemporary Sound Art and Popular Music

It is increasingly evident that popular music is utilized or appropriated as a point of reference in the works of various contemporary sound artists. Not only are artists sampling visual, material and sonic elements of popular music culture, they are doing so with an unprecedented awareness of issues within the sonic realm. To analyze the use of popular music materials in sound-based art, this MRP examines works by Dave Dyment, Laurel Woodcock and Christof Migone, three contemporary artists currently based in Toronto. In addition to negotiating critical issues in the field of sound, the artists represent the audible through various media and modes of perception. Dyment, Migone and Woodcock employ practices of sampling, appropriation and assemblage to probe popular music’s visual, material, textual and sonic composition, as well as to raise questions regarding issues of consumerism, identity and affect in culture at large

Assembly Modulated by Particle Position and Shape: A New Concept in Self-Assembly

In this communication we outline how the bespoke arrangements and design of micron-sized superparamagnetic shapes provide levers to modulate their assembly under homogeneous magnetic fields. We label this new approach, ‘assembly modulated by particle position and shape’ (APPS). Specifically, using rectangular lattices of superparamagnetic micron-sized cuboids, we construct distinct microstructures by adjusting lattice pitch and angle of array with respect to a magnetic field. Broadly, we find two modes of assembly: (1) immediate 2D jamming of the cuboids as they rotate to align with the applied field (rotation-induced jamming) and (2) aggregation via translation after their full alignment (dipole-dipole assembly). The boundary between these two assembly pathways is independent on field strength being solely a function of the cuboid’s dimensions, lattice pitch, and array angle with respect to field—a relationship which we capture, along with other features of the assembly process, in a ‘phase diagram’. In doing so, we set out initial design rules to build custom made assemblies. Moreover, these assemblies can be made flexible thanks to the hinged contacts of their particle building blocks. This flexibility, combined with the superparamagnetic nature of the architectures, renders our assembly method particularly appropriate for the construction of complex actuators at a scale hitherto not possible

Compact Polyelectrolyte Complexes: “Saloplastic” Candidates for Biomaterials

Precipitates of polyelectrolyte complexes were transformed into rugged shapes suitable for bioimplants by ultracentrifugation in the presence of high salt concentration. Salt ions dope the complex, creating a softer material with viscous fluid-like properties. Complexes that were compacted under the centrifugal field (CoPECs) were made from poly(diallyldimethyl ammonium), PDADMA, as polycation, and poly(styrene sulfonate), PSS, or poly(methacrylic acid), PMAA, as polyanion. Dynamic mechanical testing revealed a rubbery plateau at lower frequencies for PSS/PDADMA with moduli that decreased with increasing salt concentration, as internal ion pair cross-links were broken. CoPECs had significantly lower modulii compared to similar polyelectrolyte complexes prepared by the “multilayering ” method. The difference in mechanical properties was ascribed to higher water content (located in micropores) for the former and, more importantly, to their nonstoichiometric polymer composition. The modulus of PMAA/PDADMA CoPECs, under physiological conditions, demonstrated dynamic mechanical properties that were close to those of the nucleus pulposus in an intervertebral disk

Permeability of DOPC bilayers under photoinduced oxidation: Sensitivity to photosensitizer.

The modification of lipid bilayer permeability is one of the most striking yet poorly understood physical transformations that follow photoinduced lipid oxidation. We have recently proposed that the increase of permeability of photooxidized 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers is controlled by the time required by the oxidized lipid species to diffuse and aggregate into pores. Here we further probe this mechanism by studying photosensitization of DOPC membranes by methylene blue (MB) and DO15, a more hydrophobic phenothiazinium photosensitizer, under different irradiation powers. Our results not only reveal the interplay between the production rate and the diffusion of the oxidized lipids, but highlight also the importance of photosensitizer localization in the kinetics of oxidized membrane permeability

Perception of Gender in Video Games

Through a combination of a focus group and interview, participants expressed their thoughts and opinions on the gender and violence in video games. My results found that when games allow for players to create their own character and avatar, then the actions both males and females can take are exactly the same and non-gendered. In non-avatar creation games, female characters make up a vast minority with less powerful attacks.   Faculty Mentor: Kalyani Thurairajah Department: Sociolog

Asymmetric Oxidation of Giant Vesicles triggers Curvature-associated Shape Transition and Permeabilization. Running title: Oxidation of Vesicles produces Curvature

International audience(200 words) Oxidation of unsaturated lipids is a fundamental process involved in cell bioenergetics as well as in cell death. Using giant unilamellar vesicles and a chlorin photosensitizer, we asymmetrically oxidized the outer or inner monolayers of lipid membranes. We observed different shape transitions such as oblate to prolate and budding, which are typical of membrane curvature modifications. The asymmetry of the shape transitions is in accordance with a lowered effective spontaneous curvature of the leaflet being targeted. We interpret this effect as a decrease in the preferred area of the targeted leaflet compared to the other, due to the secondary products of oxidation (cleaved-lipids). Permeabilization of giant vesicles by light-induced oxidation is observed after a lag and is characterized in relation with the photosensitizer concentration. We interpret permeabilization as the opening of a pore above a critical membrane tension, resulting from the budding of vesicles. The evolution of photosensitized giant vesicle lysis tension was measured and yields an estimation of the effective spontaneous curvature at lysis. Additionally photo-oxidation was shown to be fusogenic

Hémifusion de vésicules géantes (caractérisation d'un état intermédiaire vers la fusion, en présence de forces spécifiques)

Nous avons étudié l'interaction entre deux vésicules géantes pour modéliser la fusion membranaire, un processus biologique impliqué entre autres dans l'infection virale et la communication intra- et extracellulaire. La fusion dans la cellule est déclenchée par l'action de protéines fusogènes qui, dans une des étapes, rapprochent deux membranes opposées jusqu'à une faible distance intermembranaire. Dans notre système, le rapprochement des membranes est induit par l'attraction spécifique entre lipides portant des nucléotides adénine et thymine sur leur tête. Nous avons estimé numériquement la distance d'équilibre entre deux bicouches, elle décroît de 2,6 nm sans forces spécifiques à 1,4 nm en présence de forces spécifiques. Deux vésicules sont micromanipulées afin d'être placées en contact. Un mélange partiel des lipides et une indépendance des milieux internes sont observés en microscopie de fluorescence. Le mélange partiel des lipides est quantifié; il correspond à un mélange complet des monocouches externes avec une indépendance des monocouches internes. Ces observations caractérisent un état intermédiaire vers la fusion: l'hémifusion. La cinétique de redistribution des lipides entre les deux vésicules est mesurée; elle est indépendante de la proportion de lipides fonctionnalisés, mais s'accorde bien dans la plupart des cas à un modèle de diffusion sur une "cacahouète ". Cet accord est compatible avec la présence d'au moins quelques pédoncules à l'interface entre les vésicules. Des événements de fusion complète sont parfois observés, ce qui nous ouvre des perspectives pour obtenir une fusion complète de manière reproductible.We studied the interaction between two giant vesicles to model membrane fusion, a biological process involved in viral infection and in intra- and extra-cellular communication. Fusion in the cell is induced by the action of fusogenic proteins which bring closer two opposing membranes to a short intermembrane distance. In our system, the bringing together of the membranes is induced by a specific attraction between functionalized lipids carrying adenine or thymine nucleotides on their head. We numerically estimated the equilibrium distance between two membranes, which decreases from 2.6 nm without specific forces to 1.4 nm when specific forces are present. Two vesicles are micromanipulated in order to place them into contact. A partial mixing of the lipids and an independence of the inner mediums are observed by fluorescence microscopy. The partial mixing of the lipids is quantified; it corresponds to a complete mixing of the external monolayers with an independence of the internal monolayers. These observations are characteristic of an intermediate state towards fusion: hemifusion. The kinetics of redistribution of the lipids between the two vesicles is measured; it is independent of the proportion of functionalized lipids, but agrees well in most cases with a model of diffusion on a "peanut". This agreement is consistent with the presence of at least a few stalks at the interface between the vesicles. Some full-fusion events are sometimes observed, which open up new prospects for obtaining reproducible full-fusion in our systemORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF