A photoelectron microscope with a magnetic projections lens incorporating a cyclotron orbit radius filter. The invention thus relates to the plants, seeds and tissue cultures of the variety I139593, and to methods for producing a corn plant produced by crossing a corn plant of variety I139593 with itself or with another corn plant, such as a plant of another variety. A query is obtained and semantic key terms of the query are identified. Arrangements for limiting rotation of the needle hub and needle guard housing are provided, as is a protective shroud to reduce the risk of inadvertent activation of the needle guard.