Spero C. Nicholas

Research Interests

Spero is primarily involved in the development and implementation of computational models of the vertebrate phototransduction cascade, and the numerical optimization of these models to account for a wide array of physiological data. He has written extensive code for the analysis of single-cell recordings, and collaborates on a number of projects. Currently he is working to develop a single biochemical model capable of explaining a large dynamic range of rod behavior, from single-photon reponses to highly saturated responses eliciting light adaptation mechanisms.

Education

Experience

Lead engineer in support of posturographic experiments in the Neurosciences division of the Life Science Research Laboratories at NASA's Johnson Space Center. Developed and encoded biomechanical models and analysis algorithms, conducted tests on astronauts/cosmonauts, and maintained related hardware systems, to characterize vestibular deficits and recovery following adaptation to microgravity in spaceflight.

Evaluated and revised the biomechanical algorithms of a commercial ergonomics software package that evaluated task safety by estimating joint torque/strength ratios using minimal and/or imprecise measurements that might be readily obtained in an industrial workplace.

Publications

Navid A, Nicholas SC, and Hamer RD. (2006). A proposed role for all-trans retinal in regulation of rhodopsin regeneration in human rods. Vision Research 46: 4449-4463.

Nicholas SC, and Hamer RD. (2006) Changes in the period of photocurrent saturation can provide erroneous estimates of true underlying changes in early phototransduction gain: a theoretical analysis. Invest. Ophthamlmol. Vis. Sci. 47: E-Abstract 3744. Abstract

Hamer RD, Nicholas SC, Tranchina D, Lamb TD, and Jarvinen, JLP. (2005). Toward a unified model of vertebrate rod phototransduction. Visual Neuroscience 22: 417-436. Abstract

Hamer RD, Nicholas SC, Tranchina D, Jarvinen JLP, and Lamb TD. (2004) Towards a unified model of vertebrate rod phototransduction, from single-photon to highly saturating responses. Invest. Ophthamlmol. Vis. Sci. 45: E-Abstract 2212. Abstract

Hamer RD, Nicholas SC, Tranchina D, Liebman PA, and Lamb TD. (2003). Multiple steps of phosphorylation of activated rhodopsin can account for the reproducibility of vertebrate rod single-photon responses. J. Gen. Physiol. 122: 419-444. PDF

Hamer RD, Nicholas SC, Tranchina D, Lamb TD, and Liebman PA. (2003) On the reproducibility of rod single-photon responses: the Gordian knot of phototransduction unraveled. Presented at the Annual Meeting of the European Conference on Visual Perception, Paris , France , Sept. 1-4. Abstract

Hamer RD, Nicholas SC, and Tranchina D. (2003) Reproducibility of the single-photon response (SPR) of retinal rods: rigorous tests and predictions of a multiple phosphorylation (MPn) model. Invest. Ophthamlmol. Vis. Sci. 44: E-Abstract 1518. Abstract

Hamer RD, Nicholas SC, Tranchina D, and Liebman PA. (2002). On the reproducibility of single photon responses (SPRs): the Gordian knot of rod phototransduction perseveres [Abstract]. Journal of Vision 2(10): 113a. Abstract

Hamer RD, Nicholas SC, Tranchina D, and Liebman PA. (2002) A full stochastic molecular model of phototransduction: testing theories for the reproducibility of the vertebrate rod single photon response. Invest. Ophthamlmol. Vis. Sci. 43: E-Abstract 1411. Abstract

Nicholas SC, Doxey-Gasway DD, and Paloski WH. (1998). A link-segment model of upright human posture for analysis of head-trunk coordination. J. Vestibular Research 8(3): 187-200.

Paloski WH, Kozlovskaya IB, Shestakov MP, Nicholas SC, Ivanov AM, and Reschke MF. Balance control deficits following long-duration space flight. 12th Man in Space Symposium, Washington, DC, June 8-13, 1997.

Paloski WH and Nicholas SC. On estimating relative postural stability. Presented at The Engineering Foundation's Ninth International Conference on Biomechanics and Neural Control of Movement, Mt. Sterling, OH, June 1-6, 1996.

Redfern MS and Nicholas SC. (1994). Kinematic response to galvanic stimulation in man. In: Vestibular and Neural Front, Eds. Taguchi K, Igarshi M, and Mori S. Amsterdam: Elsevier.

Contact Information

Smith-Kettlewell Eye Research Institute
2318 Fillmore St.
San Francisco, CA 94115
(415) 345-2138

spero@ski.org