An investigation for the development of an integrated optical data preprocessor

A laboratory model of a 16 channel integrated optical data preprocessor was fabricated and tested in response to a need for a device to evaluate the outputs of a set of remote sensors. It does this by accepting the outputs of these sensors, in parallel, as the components of a multidimensional vector descriptive of the data and comparing this vector to one or more reference vectors which are used to classify the data set. The comparison is performed by taking the difference between the signal and reference vectors. The preprocessor is wholly integrated upon the surface of a LiNbO3 single crystal with the exceptions of the source and the detector. He-Ne laser light is coupled in and out of the waveguide by prism couplers. The integrated optical circuit consists of a titanium infused waveguide pattern, electrode structures and grating beam splitters. The waveguide and electrode patterns, by virtue of their complexity, make the vector subtraction device the most complex integrated optical structure fabricated to date

Spin-spin correlators in Majorana representation

In the Majorana representation of a spin 1/2 we find an identity which relates spin-spin correlators to one-particle fermionic correlators. This should be contrasted with the straightforward approach in which two-particle (four-fermion) correlators need to be calculated. We discuss applications to the analysis of the dynamics of a spin coupled to a dissipative environment and of a quantum detector performing a continuous measurement of a qubit's state

Feasibility investigation of integrated optics Fourier transform devices

The possibility of producing an integrated optics data processing device based upon Fourier transformations or other parallel processing techniques, and the ways in which such techniques may be used to upgrade the performance of present and projected NASA systems were investigated. Activities toward this goal include; (1) production of near-diffraction-limited geodesic lenses in glass waveguides; (2) development of grinding and polishing techniques for the production of geodesic lenses in LiNbO3 waveguides; (3) development of a characterization technique for waveguide lenses; and (4) development of a theory for corrected aspheric geodesic lenses. A holographic subtraction system was devised which should be capable of rapid on-board preprocessing of a large number of parallel data channels. The principle involved is validated in three demonstrations

An investigation for the development of an integrated optical data preprocessor

The successful fabrication and demonstration of an integrated optical circuit designed to perform a parallel processing operation by utilizing holographic subtraction to simultaneously compare N analog signal voltages with N predetermined reference voltages is summarized. The device alleviates transmission, storage and processing loads of satellite data systems by performing, at the sensor site, some preprocessing of data taken by remote sensors. Major accomplishments in the fabrication of integrated optics components include: (1) fabrication of the first LiNbO3 waveguide geodesic lens; (2) development of techniques for polishing TIR mirrors on LiNbO3 waveguides; (3) fabrication of high efficiency metal-over-photoresist gratings for waveguide beam splitters; (4) demonstration of high S/N holographic subtraction using waveguide holograms; and (5) development of alignment techniques for fabrication of integrated optics circuits. Important developments made in integrated optics are the discovery and suggested use of holographic self-subtraction in LiNbO3, development of a mathematical description of the operating modes of the preprocessor, and the development of theories for diffraction efficiency and beam quality of two dimensional beam defined gratings

Evaporated As2S3 Luneburg lenses for LiNbO3:Ti optical waveguides

Luneburg lenses of good quality were formed on high index optical waveguides by evaporation of arsenic trisulfide glass through simple masks. Using only two thin circular aperture masks, lenses with focal spots of a few times the diffraction limited width at f/4 were obtained. These lenses were designed for and tested at both visible (633 nm) and infrared wavelengths. Procedures for the design, fabrication, and testing of lenses of this type are described

A Majorana Fermion t-J Model in One Dimension

We study a rotation invariant Majorana fermion model in one dimension using diagrammatic perturbation theory and numerical diagonalization of small systems. The model is inspired by a Majorana representation of the antiferromagnetic spin-1/2 chain, and it is similar in form to the t-J model of electrons, except that the Majorana fermions carry spin-1 and Z_2 charge. We discuss the implications of our results for the low-energy excitations of the spin-1/2 chain. We also discuss a generalization of our model from 3 species of Majorana fermions to N species; the SO(4) symmetric model is particularly interesting.Comment: 29 LaTeX pages, 11 postscript figure

Collaborative writing with young people with disabilities: raising new questions of authorship and agency

The process of communication between author and reader is a critical issue in examining any text. When considering the communication of ideas from young people whose voices are seldom heard, the journey from author to audience has particular significance. The construction of children and young people as ‘authors’ is important, especially for those with learning difficulties or who struggle to comply with the current emphasis on spelling, punctuation and grammar. This article relates to a UK Research-Council-funded three-year collaborative research project involving the co-creation of fictional stories with young people with disabilities to represent aspects of their lives. Drawing on frameworks from narratology, I analyse the co-creation of one of the stories, and present an interpretation and elaboration of the discourse structure of narrative fiction to illustrate the complexities of the relationship between the multi-faceted ‘author’ and community ‘reader’ of these stories. The combination of qualitative research and fictional prose has particular characteristics and implications for the dissemination and communication of research findings; while extending feminist critique of Barthes’ claim for the death of the author provides new insights for engaging children in writing with their own voice

Channelling figurativity through narrative : the paranarrative in fiction and non-fiction

Contrary to wide-spread assumptions, metaphor in narrative is not a pre-established, extra-textual form appearing in different instances of discourse, but rather an event resulting from a strategic distribution of information in the narrative process. Hence, the appeal to conceptual cultural knowledge is to be considered as a consequence, and not as a prerequisite of metaphor interpretation. By means of the concept of the paranarrative, we highlight the rhetorical interconnectedness of metaphor with other figures of speech (such as metonymy) and we explore the narrative integration of diacritic forms of indirectness. In order to illustrate the terminology that can address these focal concerns, the paper discusses the relation between tropes and narrative, via selected examples from narrative texts (both fictional and non-fictional) written by Juli Zeh, Herta Müller, Jürgen Nieraad, and Siddhartha Mukherjee. As their common denominator, these examples channel through narrative figurative domains considered to be known intuitively to wit: personifications; iconic pars pro toto references to concentration camps; and metaphors for cancer in disease biographies

The sadism of the author or the masochism of the reader?

The symposium giving rise to this collection and the thriving of the B.S. Johnson Society both indicate that there is something exceptional going on with the literary and academic community’s relationship with this author, something we (collectively) still haven’t quite fathomed. In order to attempt to identify the source of Johnson’s fascination, I want to discuss the author-reader relationship as it comes into focus in his novels since, implicitly and explicitly, this is a recurring issue in academic studies of Johnson’s work (see White 2011)