David Gershon

Vision servo control of a robotic sewing system

The FIGARO robotic sewing system was developed to perform assembly and handling operations on cloth. A flexible automation approach was adopted, in which the robot was required to control the cloth panel during both handling and sewing operations, without the aid of hard automation attachments that might limit the flexibility of the system. A technique was developed for producing a seam parallel to an edge of arbitrary contour, which was based on sensory serving of the robot. The development of the seam width control system is described. It was designed using simulation studies that took into account the control transfer function and nonlinearities such as camera pixel resolution, time delays and robot motion limitations. Satisfactory performance was achieved for sewing speeds up to 3000 r.p.m. for typical cloth panel curvatures.<<ETX>>

The temporal relationships of protein and DNA synthesis in polyoma virus development

Abstract The temporal relationships of protein and DNA synthesis involved in polyoma virus (PV) development in mouse embryo cells, were studied by the use of puromycin and the assay of infections DNA. Studies with puromycin showed that protein synthesis necessary for PV development started at 8–9 hours after infection. The full complement of proteins necessary for PV maturation first appeared 14–16 hours after infection. Increase in the amount of infectious DNA started at 12–14 hours after infection. Puromycin was shown to prevent the production of infectious DNA. Some of the steps involved in PV development can thus be outlined as follows: early proteins appear at 8–9 hours after infection, viral DNA synthesis starts at 12–14 hours, late proteins required for virus production appear at 14–16 hours, and virions were first detected at 22–24 hours after infection.

Resistance and susceptibility to challenge infection of polyoma-induced tumor cell clones

Abstract Resistance to challenge infection with polyoma virus (PV) was studied in 77 clones derived from a PV-induced mouse mammary tumor and in 9 clones derived from a PV-induced mouse parotid tumor clone. There was no spontaneous virus production in cultures of any of these clones. Cloning of 2 uncloned resistant mass populations of the mammary tumor yielded 55% susceptible clones, while cloning of 2 susceptible clones derived from this tumor yielded 7% and 37% resistant clones. The derivation of resistant from susceptible clones was observed through two cycles of recloning. Although the uncloned resistant populations thus gave rise to susceptible clones, and susceptible clones gave rise to resistant clones, resistant clones derived from the mammary and parotid tumor produced only resistant clones. Two susceptible clones and an uncloned susceptible mass population became resistant after a series of transplantations in mice, a result suggesting a selective advantage for resistant cells in vivo . PV inoculation of the grafted mice inhibited in vivo growth after cell grafting, both with a resistant and a susceptible clone. There was no apparent correlation between observed differences in the karyotypes of the tumor cells and their reaction to challenge infection. Clones of PV-induced tumors that were resistant to PV challenge infection supported multiplication of mouse encephalomyocarditis virus. It is concluded that resistance of PV-induced tumor cells to PV challenge infection differs in some respects from the immunity of lysogenic bacteria to superinfection.

The early synthesis of RNA in polyoma virus development

Abstract The synthesis of RNA during polyoma virus (PV) development has been studied by the use of 6-azauridine in the presence of added deoxycytidine and thymidine. The results indicate that the RNA required for PV development was present in infected mouse embryo cells by about 9 hours after infection, i.e., about 14 hours before virions were first detected; and that RNA synthesis was required for the synthesis of infectious DNA as well as for the production of viral antigen and virions.