Letter from Geo[rge] W. Kehr to William F. Bade, 1910 Jul 25.

J. HORACE, McFARLAND, President, Harrisburg, Pa.CLINTON ROGERS WOODRUFF. First Vice-President, PhiladelphiaWILLIAM B. HOWLAND, Treasurer, New YorkRICHARD B. WATROUS, Secretary, Washington, D. C.Vice-President: JAMES R. GARFIELD, Cleveland, OhioJOHN WESLEY HILL, D. D., New YorkW. W. HANNAN, Detroit, Mich.GEORGE W. MARSTON, San Diego, Cal.MRS. EDWARD W. BIDDLE. Carlisle, Pa.American Civic AssociationMAIN OFFICE: WASHINGTON, D. C.Executive BoardDr. JOHN QUINCY ADAMS, New YorkHENRY A. BARKER, Providence, R. I.FRANK CHAPIN BRAY, New YorkMISS MARY MARSHALL BUTLER, Yonkers. N. Y.DR. KENYON L. BUTTERFIELD, Amherst, Mass.MRS. CAROLINE BARTLETT CRANE, Kalamazoo, Mich.MAIN OFFICE: WASHINGTON, D. C.Executive BoardGEORGE OTIS DRAPER, New YorkFREDERICK L. FORD. Hartford, Conn.EDWARD HATCH, JR., New YorkJ. L. HUDSON, Detroit, Mich.MRS. MELVILLE F. JOHNSTON. Richmond, Ind.HARLAN P. KELSEY, Salem, Mass.Executive BoardWARREN H. MANNING, Boston, Mass.MRS. A. H. McCREA, Chicago, III.MRS. EDWIN F. MOULTON, Warren, OhioJOHN NOLEN, Cambridge, Mass.GRAHAM ROMEYN TAYLOR. Chicago, III.BRAINARD H. WARNER, Washington, D.C.OFFFICE OF THE PRESIDENTHARRISBURG, PA.July 25, 1910Mr. William F. Bade,The Independent,130 Fulton Street, N. Y.Dear Sir: Yours of July 23, enclosing a galley proof of an editorial that will appear in The Independent issue of July 28, is received in Mr. McFarland\u27s absence, and will be forwarded to him to New York, in care of the Suburban Life office, where he will probably be until tomorrow evening.Yours truly,GWK/W [illegible]Secretary to Mr. McFarland0628

General technique of calculating drift velocity and diffusion coefficient in arbitrary periodic systems

We develop a practical method of computing the stationary drift velocity V and the diffusion coefficient D of a particle (or a few particles) in a periodic system with arbitrary transition rates. We solve this problem both in a physically relevant continuous-time approach as well as for models with discrete-time kinetics, which are often used in computer simulations. We show that both approaches yield the same value of the drift, but the difference between the diffusion coefficients obtained in each of them equals V*V/2. Generalization to spaces of arbitrary dimension and several applications of the method are also presented.Comment: 12 pages + 2 figures, RevTeX. Submitted to J. Phys. A: Math. Ge

Performance of Certified Seed Lots of Dawson Alfalfa

Breeder, foundation, and certified seed lots of Dawson alfalfa, Medicago sativa L., were tested to determine stability in performance during three generations of seed increase under certification. Two field experiments were conducted, a seeded forage yield test and a space-planted test. Greenhouse experiments included separate tests for resistance to pea aphids, spotted alfalfa aphids, and bacterial wilt. Results obtained on certified Dawson alfalfa seed classes in field and greenhouse experiments were in agreement with the original variety description

Toy model for molecular motors

A hopping model for molecular motors is presented consisting of a state with asymmetric hopping rates with period 2 and a state with uniform hopping rates. State changes lead to a stationary unidirectional current of a particle. The current is explicitly calculated as a function of the rate of state changes, including also an external bias field. The Einstein relation between the linear mobility of the particle and its diffusion coefficient is investigated. The power input into the system is derived, as well as the power output resulting from the work performed against the bias field. The efficiency of this model is found to be rather small.Comment: 11 pages Latex, 7 postscript figures, to be published in Physica

Mean-Field Treatment of the Many-Body Fokker-Planck Equation

We review some properties of the stationary states of the Fokker - Planck equation for N interacting particles within a mean field approximation, which yields a non-linear integrodifferential equation for the particle density. Analytical results show that for attractive long range potentials the steady state is always a precipitate containing one cluster of small size. For arbitrary potential, linear stability analysis allows to state the conditions under which the uniform equilibrium state is unstable against small perturbations and, via the Einstein relation, to define a critical temperature Tc separating two phases, uniform and precipitate. The corresponding phase diagram turns out to be strongly dependent on the pair-potential. In addition, numerical calculations reveal that the transition is hysteretic. We finally discuss the dynamics of relaxation for the uniform state suddenly cooled below Tc.Comment: 13 pages, 8 figure

Hopping motion of lattice gases through nonsymmetric potentials under strong bias conditions

The hopping motion of lattice gases through potentials without mirror-reflection symmetry is investigated under various bias conditions. The model of 2 particles on a ring with 4 sites is solved explicitly; the resulting current in a sawtooth potential is discussed. The current of lattice gases in extended systems consisting of periodic repetitions of segments with sawtooth potentials is studied for different concentrations and values of the bias. Rectification effects are observed, similar to the single-particle case. A mean-field approximation for the current in the case of strong bias acting against the highest barriers in the system is made and compared with numerical simulations. The particle-vacancy symmetry of the model is discussed.Comment: 8 pages (incl. 6 eps figures); RevTeX 3.

Relaxation at late stages in an entropy barrier model for glassy systems

The ground state dynamics of an entropy barrier model proposed recently for describing relaxation of glassy systems is considered. At stages of evolution the dynamics can be described by a simple variant of the Ehrenfest urn model. Analytical expression for the relaxation times from an arbitrary state to the ground state is derived. Upper and lower bounds for the relaxation times as a function of system size are obtained.Comment: 9 pages no figures. to appear in J.Phys. A: Math. and Ge

Management of Four Alfalfa Varieties to Control Damage from Potato Leafhoppers

The main purpose of this study was to obtain information on forage yield and quality of four alfalfa (Medicago sativa L.) varieties that differed in level of resistance to potato leafhopper (Empoasca fabae Harris) yellowing, when cut at three stages of growth in the second and third cuttings in field plots, with and without insecticide application. The stages of growth were bud, 1/10, and full bloom. Other purposes included study of the same varieties in field cages manually infested at 20, 40, and 60 adult leafhoppers/square yard, and in supplemental cuttings of field plots under high natural infestation levels