Charles Roberts

Galactokinase-deficient mutants of Tetrahymena thermophila: selection and characterization.

SummaryWe have isolated a series of mutants of Tetrahymena thermophila which are resistant to inhibition of growth by the galactose analog, 2-deoxygalactose. These mutants were obtained after mutagenesis with nitrosoguanidine and the induction of cytogamy to permit the recovery of recessive mutations induced in the germline micronucleus. Resistance to 2-deoxygalactose is correlated with a decreased rate of growth in galactose minimal medium and greatly reduced levels of galactokinase. The resistant phenotype of the mutants is apparently due to the galactokinase deficiency, which prevents the accumulation of toxic phosphorylated metabolites of 2-deoxygalactose. Genetic analyses reveal that the 2-deoxygalactose resistance alleles segregate as single Mendelian loci. The galactokinase-deficient strains described here represent the first mutants in this organism for which the biochemical basis of the mutant phenotype is known. These mutants, as well as others isolated similarly, should be of value in the elucidation of the mechanisms governing galactokinase gene regulation and in improving techniques of selection for other recessive mutations in Tetrahymena.

Gibber: Abstractions for Creative Multimedia Programming

We describe design decisions informing the development of Gibber, an audiovisual programming environment for the browser. Our design comprises a consistent notation across modalities in addition to high-level abstractions affording intuitive declarations of multimodal mappings, unified timing constructs, and rapid, iterative reinvocations of constructors while preserving the state of audio and visual graphs. We discuss the features of our environment and the abstractions that enable them. We close by describing use cases, including live audiovisual performances and computer science education.

Designing musical instruments for the browser

Native Web technologies provide great potential for musical expression. We introduce two JavaScript libraries towards this end: Gibberish.js, providing heavily optimized audio DSP, and Interface.js, a GUI toolkit that works with mouse, touch, and motion events. Together they provide a complete system for defining musical instruments that can be used in both desktop and mobile Web browsers. Interface.js also enables control of remote synthesis applications via a server application that translates the socket protocol used by Web interfaces into both MIDI and OSC messages. We have incorporated these libraries into the creative coding environment Gibber, where we provide mapping abstractions that enable users to create digital musical instruments in as little as a single line of code. They can then be published to a central database, enabling new instruments to be created, distributed, and run entirely in the browser.

Spatial Interaction in a Multiuser Immersive Instrument

The AlloSphere provides multiuser spatial interaction through a curved surround screen and surround sound. Two projects illustrate how researchers employed the AlloSphere to investigate the combined use of personal-device displays and the shared display. Another two projects combined multiuser interaction with multiagent systems. These projects point to directions for future ensemble-style collaborative interaction.

Sound-Light Giblet

We describe an audiovisual live coding performance created using Gibber, a creative coding environment that runs in the browser. The performance takes advantage of novel affordances for rapidly creating music, shaders, and mappings that tie together audio and visual modalities.