1,839 research outputs found
Diagnostic Alleles From Electrophoresis Distinguish Two Noctuid Pest Species, \u3ci\u3eHydraecia Immanis\u3c/i\u3e and \u3ci\u3eH. Micacea\u3c/i\u3e (Lepidoptera: Noctuidae).
Native hop vine borer (Hydraecia immanis) and introduced potato stem borer (H. micacea) populations in Midwest corn have reached noticeable levels near the Great Lakes plant community ecotone between boreal forests and temperate deciduous forests. The hop vine borer is more specialized in its diet and occurs in corn generally south of the plant community ecotone, whereas the potato stem borer is polyphagous and occurs in corn mostly north of the Great Lakes plant transition zone. We analyzed the genetic composition of each species using cellulose acetate electrophoresis and resolved 19 loci of which 6 exhibited fixed or nearly fixed allelic differences. We expect that this will be useful in determining the degree of hybridization where the two species become sympatric due to expected continued range expansions in Michigan, Wisconsin, and New York State
Large angle Beamstrahlung as a beam-beam monitoring tool
A novel method to measure the beam-beam interaction in e+e- colliders is
presented.Comment: 17 pages, four figures, to be published in Nuclear Instruments and
Method
Leaving the campus ministry: critical factors in vocational change
Thesis (Ph.D.)--Boston UniversityThe problem of this dissertation is to investigate the critical factors in why men leave the campus ministry. Those entering have not been making it a life-long ministry. Many leave it before they are forty years old to take a parish church or a teaching position.
The method chosen was a questionnaire study on those men who left the campus ministry. The subjects included:
1. full-time campus ministers
2. male
3. ordained
4. who served during at least five calendar years
5. who left the profession between 1950 and 1962
6. and who belong to the denominations or agency included in the National Student Christian Federation. [TRUNCATED
Feedback linearization, invertibility of map, zero dynamics, and nonlinear control of the space station
Based on feedback linearization and ultimate boundedness theory, a new approach to attitude control of the space station using control moment gyros (CMG\u27s) is presented. A linearizing transformation is derived to obtain a simple linear representation of the nonlinear pitch axis dynamics. A feedback control law for trajectory tracking is derived when there is no disturbance torque acting on the space station. For attitude control in the presence of uncertain torque input, an additional control signal is superimposed such that in the closed-loop system, attitude responses are uniformly ultimately bounded and tend to a small set of ultimate boundedness. Extension of this approach to linearization of the coupled yaw and roll axis dynamics and control is presented. Simulation results for the pitch axis control are obtained to show that in the closed-loop system precise attitude control is accomplished. (Abstract shortened with permission of author.)
Design of a RF Gun for Heavy Beam Loading
For the drive beam generation of the CLIC Test Facility, a RF photo electron gun is required to generate a charge of 1 uC in a train of 48 bunches. The extracted beam energy of 6.5 J leads to a pronounced decrease of the field gradient, causing strong variations in the transverse and longitudinal beam dynamics. The drop in beam momentum yields a variation in focusing of the following solenoid leading to a blow-up of the transversal emittance. A second effect is the change of the bunch spacing caused by differing bunch velocities. These effects are to a large extent determined by the beam loading in the first cell, which contains the photo cathode. In order to reduce this effect with moderate expense of RF power, a new gun design has been developed using a TM02 resonance in the first cell followed by two standard TM01 cells. Beam simulations show that with this gun, the overall change in the longitudinal bunch spacing can be strongly reduced. Also the chromatic effects in the solenoid due to the drop in longitudinal momentum are partially compensated
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