Showing papers on "Crossover published in 1983"

Weak crossover and move α in Japanese

Abstract: We have argued that if we adopt an account of weak crossover that utilizes the notion antecedent-of, the weak crossover facts in Japanese can be accounted for under some independently motivated assumptions. In particular, under this approach, the absence of the weak crossover effect in (8b) ceases to be a problem for the hypothesis that scrambling is an instance of Move α. Since there are some phenomena that independently indicate that scrambling is to be analyzed in terms of Move α, the scrambling facts discussed in this short paper constitute evidence for the necessity of the notion antecedent-of.

Optimal crossover designs in the presence of carryover effects.

Abstract: Under either the random patient-effect model with sequence effects or the fixed patient-effect model, the usual two-period, two-treatment crossover design, AB,BA, cannot be used to estimate the contrast between direct treatment effects when unequal carryover effects are present. If baseline observations are available, the design AB,BA can validly be used to estimate a treatment contrast. However, the design AB,BA,AA,BB with baseline observations is more efficient. In fact, we show that this design is optimal whether or not baseline observations are available. For experiments with more than two periods, universally optimal designs are found for both models, with and without carryover effects. It is shown that uncertainty about the presence of carryover effects is of little or no consequence, and the addition of baseline observations is of little or no added value for designs with three or more periods; however, if the experiment is limited to only two periods the investigator pays a heavy penalty.

Crossover to equivalent-neighbor multicritical behavior in arbitrary dimensions

Abstract: Spin models subject to both nearest-neighbor and equivalent-neighbor interactions are studied. The free energy of these models is related to the free energy of the nearest-neighbor spin models in a magnetic field. The scaling exponent for equivalent-neighbor interactions is calculated, and crossover from Ising to mean-field criticality is described in arbitrary dimensions. Interesting multicritical behavior is observed for antiferromagnetic nearest-neighbor interactions.

An E. M. Method for Earth Resistivity Measurements Using Power Line Harmonic Fields

Abstract: An experiment was carried out to infer ground conductivity by making use of magnetic fields created by a power line carrying electric currents as source signals for E. M. exploration. The experiment was done in an area, 10km×10km approximately, which is under an overwhelming influence of a major 3 phase a. c. power line. It runs generally east-west and south of the area. The magnetic field measurement showed that the 60Hz, 180Hz, 300Hz, and 420Hz signals were the four strongest harmonic components. A plot of the field measurements along a northsouth line, normalized to the value at a reference station, shows that the vertical magnetic field strength decreases inversely with the distance from the power line in the vicinity of the source and to the cubic inverse of the distance further from the source. The crossover distance (between the 1/r relation and 1/r3 relation) is dependent on frequency. Extension of an existing theory predicts this trend with the crossover distance √2 times greater than the skin depth, providing that the Earth is considered a uniform conductor. The effective resistivity is inferred to be of the order of 104Ωm from the crossover distance for 300Hz and 420Hz. No crossover is seen for 60Hz, and for 180Hz, the fall-off ∝ 1/r3 begins to take place near the edge of the survey area (-10km in distance from the power line). A deviation from the general trend occurs at the same location for all four frequencies. A change in geologic material in the subsurface is mapped in this locality.

Corrections to dynamic scaling for the λ transition in liquid helium. II. Quasiscaling

Abstract: We give a general phenomenological treatment of the crossover of the critical dynamics from background to the asymptotic region. The log-log plot of the entropy diffusion coefficient versus wave number exhibits a point of inflexion in the crossover region. The resulting straight portion of the curve produces ''quasiscaling,'' with an apparent critical exponent 18% bigger than expected from dynamic scaling. Our k-space treatment of the crossover has some advantages over the conventional renormalization-group method. By evaluating the loop integrals in three dimensions we furthermore are able to impose rigorous conditions on the precritical rise.

Unique Trajectory Method in Migdal Renormalization Group Approach and Crossover Phenomena

Abstract: Migdal renormalization group approach, combined with Wilson· Kogut topological argu· ment, is applied to four dimensional lattice gauge theory of finite subgroup [(120) of 5U(2). i) A slight (compared with the Monte Carlo results) but clear crossover from strong coupling regime to weak coupling regime is observed for the Wilson action. ii) For mixed action, of the fundamental and the adjoint representation, a clearer stepwise transition, suggesting first order phase transition, is found at 1:S/:Iab:S3 (where /:lab denotes the bare inverse coupling constant of the adjoint representation). This stepwise transition changes into crossover for smaller /:lab iii) There are four critical lines in (/:1/, /:I:) plane starting from a quadruple point (/:1/ ~ 0.75, /:I: ~ 3.2) where /:1/ denotes the bare inverse coupling constant of the fundamental representation; 1) 50(3) critical line, 2) Z(2) critical line, 3) a critical line due to the discreteness of [(120), 4) a critical line related to crossover. In this investigation, the unique trajectory of renormal· ization group is very important and plays a powerful role in finding crossover and stepwise transition.

Crossover designs and repeated measurements.

Abstract: In crossover or changeover designs, the different treatments are allocated to each experimental unit (e.g. patient in clinical trial) in a randomized order. To analyze the results of such experiments,

Loudspeaker crossover networks

Abstract: Crossovers employing three- pole filters and a bandpass filter to linearise their input impedance combine a fast filtering action with a range of possible responses and tolerance to variations in component values. The bandpass filter to linearise the input impedance may be constructed using reactances whose values are the same as some of those used in the crossover filters. The network of figure (4) is designed to have a crossover frequency of approximately 3.2 kHz for load resistances, R, of 7.5 OMEGA . Either air-cored or ferrite cored inductors may be used. The extra circuit components to linearise the input impedances of the loudspeaker drive units have not been shown.

Cluster decimation derivation of exact percolation-thermal crossover exponent in dilute spin models

Abstract: It is shown that the decimation method of renormalisation group theory in a restricted parameter space, applied to any cluster, gives the exact unit value for the percolation-thermal crossover exponent for bond-diluted Ising, Potts and anisotropic Heisenberg models.

Crossover between Gaussian and self-avoiding limits via finite order self-avoiding walk: Conformation space renormalization for polymers. VII

Abstract: The crossover between the random walk and the self‐avoiding walk via finite order self‐avoiding random walk (FSAW) is studied analytically with the aid of conformation space renormalization group theory. Explicit expressions for the end‐vector distribution function and 〈R2〉 are given up to order e=4−d (d the spatial dimension). Since the excluded volume parameter for FSAW is contour length dependent, it is very awkward to study the present crossover behavior by using the polymer–magnet analogy. In contrast, our calculations in conformation space are simple and transparent, showing the power of this RG approach. The crossover behavior along FSAW is compared with the crossover obtained when the magnitude of the excluded volume interaction is decreased. The crossover via FSAW may occur in situations where a very long single chain is immersed in a solution of (shorter) chains and the concentration of the (shorter) chains is increased.

A model for comparisons with ordered categorical data

Abstract: A model developed by Andrich for ordered categorical data is extended to develop tests for treatment effects with paired or matched samples. In particular, this includes analysis for pre-post studies and crossover designs. Some advantages of this model are that it allows for misclassification of subjects, yields reasonable conditional requirements for exact analysis, a normal approximation is good for all but the smallest of sample sizes, and it is relatively simple mathematically. Furthermore, the form of the tests derived are logical extensions of tests for unordered categories.