Ecologies of memory

Ecologies of Memory is a short story collection that explores conceptions and fallibility of memory and how it intersects with love, belief, and the formation of identity. Processes of Erosion, the first story in the collection, addresses memory as a geological process in the form of a glacier scraping a small Alaskan town off the map. This presents the idea of memory as a topological feature: something that can\u27t necessarily be controlled, that intrudes into our homes and heads. Vespers continues this theme in the character of Bill. His wife, Anna, has just left him suddenly, and he\u27s forced to engage with two types of memory. He feels compelled to treat the instance as an investigation, pouring over manuscripts, his external memory, in order to find what went wrong. Simultaneously he\u27s attempting to fix her in place, knowing that his memory of her in ephemeral. Ultimately, akin to the glacier, he finds himself closed off, monastic life intrudes as he is unable to effectively deal with the loss. The story A Body Always, Already attempts to identify ways that memory is involved in the formation of identity. Ariel is a character in trouble. She is attempting to self-actualize, to make a life for herself, but is unable to do so, due to the identity of the self her father tried to make of her. Here her past self is intruding on the present, the mechanism being a new-age church, and she is forced to come to terms with this dissonance. The final story of the collection, Random Access returns to the character of Bill, now married to a psychiatrist named Lily. Lily is working in clinical trials using a drug that allows memories to supersede reality. Bill becomes addicted to the past, returning to his first wife and opening up the old wounds he had sealed in Vespers. As Bill seeks to perfect his memories of Anna, he comes to face the unsettling proposition that he might be remembering incorrectly, or even manufacturing memories, destroying the authenticity that gives the drug such allure. The collection ends with Lily taking the drug herself attempting to find one point of vivid happiness in her life. She cycles into the past until she at last settles on a memory of the womb, but the reader knows, tragically, that this must be a confabulation. This draws attention to the possibility that our most fondly remembered instances might be manufactured. The collection explores memory even to the degree we represent the past in fiction. Mechanisms are created to allow flashback to diagetically take place, taking the reader to the past as the characters experience it, as intrusive ecologies, taking on lives of their own

Modeling Self-Subtraction in Angular Differential Imaging: Application to the HD 32297 Debris Disk

We present a new technique for forward-modeling self-subtraction of spatially extended emission in observations processed with angular differential imaging (ADI) algorithms. High-contrast direct imaging of circumstellar disks is limited by quasi-static speckle noise and ADI is commonly used to suppress those speckles. However, the application of ADI can result in self-subtraction of the disk signal due to the disk's finite spatial extent. This signal attenuation varies with radial separation and biases measurements of the disk's surface brightness, thereby compromising inferences regarding the physical processes responsible for the dust distribution. To compensate for this attenuation, we forward-model the disk structure and compute the form of the self-subtraction function at each separation. As a proof of concept, we apply our method to 1.6 and 2.2 micron Keck AO NIRC2 scattered-light observations of the HD 32297 debris disk reduced using a variant of the "locally optimized combination of images" (LOCI) algorithm. We are able to recover disk surface brightness that was otherwise lost to self-subtraction and produce simplified models of the brightness distribution as it appears with and without self-subtraction. From the latter models, we extract radial profiles for the disk's brightness, width, midplane position, and color that are unbiased by self-subtraction. Our analysis of these measurements indicates a break in the brightness profile power law at r~110 AU and a disk width that increases with separation from the star. We also verify disk curvature that displaces the midplane by up to 30 AU towards the northwest relative to a straight fiducial midplane.Comment: Accepted for publication in ApJ, 20 pages, 10 figures, 1 tabl

Lasing and cooling in a hot cavity

We present a microscopic laser model for many atoms coupled to a single cavity mode, including the light forces resulting from atom-field momentum exchange. Within a semiclassical description, we solve the equations for atomic motion and internal dynamics to obtain analytic expressions for the optical potential and friction force seen by each atom. When optical gain is maximum at frequencies where the light field extracts kinetic energy from the atomic motion, the dynamics combines optical lasing and motional cooling. From the corresponding momentum diffusion coefficient we predict sub-Doppler temperatures in the stationary state. This generalizes the theory of cavity enhanced laser cooling to active cavity systems. We identify the gain induced reduction of the effective resonator linewidth as key origin for the faster cooling and lower temperatures, which implys that a bad cavity with a gain medium can replace a high-Q cavity. In addition, this shows the importance of light forces for gas lasers in the low-temperature limit, where atoms can arrange in a periodic pattern maximizing gain and counteracting spatial hole burning. Ultimately, in the low temperature limit, such a setup should allow to combine optical lasing and atom lasing in single device.Comment: 11 pages, 6 figure

Conceptualisations of children’s wellbeing at school: the contribution of recognition theory

A large study in Australian schools aimed to elucidate understandings of ‘wellbeing’ and of factors in school life that contribute to it. Students and teachers understood wellbeing primarily, and holistically, in terms of interpersonal relationships, in contrast to policy documents which mainly focused on ‘problem areas’ such as mental health. The study also drew on recognition theory as developed by the social philosopher Axel Honneth. Results indicate that recognition theory may be useful in understanding wellbeing in schools, and that empirical research in schools may give rise to further questions regarding theory

Site-Specific Incorporation of Selenocysteine by Genetic Encoding as a Photocaged Unnatural Amino Acid

Selenocysteine (Sec) is a naturally occurring amino acid that is also referred to as the 21st amino acid. Site-specific incorporation of Sec into proteins is attractive, because the reactivity of a selenol group exceeds that of a thiol group and thus allows site-specific protein modifications. It is incorporated into proteins by an unusual enzymatic mechanism which, in E. coli and other organisms, involves the recognition of a selenocysteine insertion sequence (SECIS) in the mRNA of the target protein. Reengineering of the natural machinery for Sec incorporation at arbitrary sites independent of SECIS elements, however, is challenging. Here we demonstrate an alternative route, whereby a photocaged selenocysteine (PSc) is incorporated as an unnatural amino acid in response to an amber stop codon, using a mutant Methanosarcina mazei pyrrolysyl-tRNA synthetase, Mm PCC2RS, and its cognate tRNACUA. Following decaging by UV irradiation, proteins synthesized with PSc are readily tagged, e.g., with NMR probes to study ligand binding by NMR spectroscopy. The approach provides a facile route for genetically encoded Sec incorporation. It allows the production of pure selenoproteins and the Sec residue enables site-specific covalent protein modification with reagents that would usually react first with naturally occurring cysteine residues. The much greater reactivity of Sec residues allows their selective alkylation in the presence of highly solvent-exposed cysteine residues.Financial support by the Australian Research Council, including a Laureate Fellowship to G.O., is gratefully acknowledged