9,914 research outputs found
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
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