Elliptic semiplanes and group divisible designs with orthogonal resolutions

In this paper we prove that there exists an elliptic semiplaneS(v, k, m) withk –m 2 if and only if there exists a group divisible design GDD _k ((k –m)(k – 1);k –m; 0, 1) withm pairwise orthogonal resolutions. As an example of this theorem, we construct an elliptic semiplaneW(45, 7, 3) and show thatW is isomorphic to the elliptic semiplaneS(45, 7, 3) given by R. D. Baker.     

Selection theorems,based on generalized variation and oscillation

In this paper we prove selection theorems for everywhere and almost everywhere convergent subsequences, based on the notion of uniformly limited oscillation, ofA, Λ-oscillation and ofA, Λ-variation, whereA is a system of intervals and Λ a sequence of reals. By this, we generalize and strengthen the selection theorems of Schrader (for oscillation) and of Waterman (for Λ-variation).     

Searching for light Higgs scalar bosons in the next generation of electron-positron collider at LEP

Thee ⁺ e ^–-collider facilities at LEP II, with the CM energy S in the range 100–170 GeV, may be able to detect light Higgs bosons, assuming a high luminosity. The production cross sections of a light Higgs bosonH ⁰ in association with the neutral gauge bosonZ ⁰ are calculated for varying ranges of the CM energy expected to be available to LEP II and VLEEP (Novosibirsk) and for various values of the light Higgs mass. It is found that production cross sections are sizable in comparison with those for the very massive Higgs bosons in proton-anti(proton) supercolliders, Tevatron, Sp¯pS, and SSC, respectively. The implication of this feature is pointed out. Further, prospects for light Higgs production in association with the charged gauge bosonW ^– in ultraenergetic neutrino beams are examined.     

Observables on hypergraphs

Observables on hypergraphs are described by event-valued measures. We first distinguish between finitely additive observables and countably additive ones. We then study the spectrum, compatibility, and functions of observables. Next a relationship between observables and certain functionals on the set of measures M(H) of a hypergraph H is established. We characterize hypergraphs for which every linear functional on M(H) is determined by an observable. We define the concept of an effect and show that observables are related to effect-valued measures. Finally, we define operational transformations from M(H) to itself and show that they can be described as a certain combination of effects.On leave from University of Berne, Institute of Mathematical Statistics, Sidlerstrasse 5, CH-3012 Berne, Switzerland.     

On the use of symmetrized dot patterns for the visual characterization of speech waveforms and other sampled data

While the spectrogram (and related graphic analyses) have been invaluable in showing the general frequency content of an input signal, sometimes it is difficult for trained and untrained users to see on the spectrogram differences which are perceptible to the ear. In this paper, several demonstrations of a novel representation are presented which, in some cases, can make subtle differences in input signals obvious to the human analyst. The representation, a "symmetrized dot pattern" (SDP), provides a stimulus in which local visual correlations are integrated to form a global percept and can potentially be applied to the detection and characterization of significant features of any sampled data.     

A two-stage nonlinear cochlear model possesses automatic gain control

A model of the cochlea is explored using as stimuli two simultaneously presented sinusoids of equal amplitude. The model consists of two stages: a linear bandpass filter, followed by a reservoir-type representation of the hair-cell/nerve-fiber complex. Fast Fourier transforms of the model's output were computed. While the amplitudes of the individual response components were strongly nonlinear functions of intensity, the ratio of the magnitudes of the response components at the frequencies of the two stimulating sinusoids was found to be nearly equal, over a wide intensity range, to the ratio of the amplitudes which those stimulating sinusoids possessed at the output of the filter. Thus the reservoir stage exerts "automatic gain control".     

Study of diffusion creep accompanying superplastic deformation of the alloy ZhS6KP

The development of diffusion creep (DC) accompanying superplastic deformation (SPD) of the highly doped nickel alloy ZhS6KP is studied based on an investigation of the redistribution of dispersed intragrain deposits of the phase of Ni₃(Al, Ti). Deposit-free zones (DFZ) are formed in the alloy, held at the temperature of SPD and accompanying deformation at the grain boundaries. The contribution of DC to the deformation was determined from a comparative analysis of the width of the DFZ in the deformed and undeformed parts of the samples for different grain sizes and rates of DC taking into account diffusion accommodation. It was established that for the optimum rate of SPD the upper limit of the contribution of DC to deformation for 2-m grains does not exceed 11%. It is concluded, based on the distribution of DFZ, that the effect of DC accompanying SPD is determined by diffusion fluxes, associated with the local concentration of stress accompanying the development of grain-boundary slipping.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 40–45, June, 1986.In conclusion, we thank Yu. M. Mishin for a useful discussion of the results.     

Gallium arsenide avalanche-type S-diode based on a n+-π-ν-n structure

The results are presented of an investigation of the electrical characteristics of avalanche S-diodes based on a new type of structure (⁺---n), which is obtained by diffusing iron in GaAs with n = 1.10¹⁷ cm^–3. The diodes have regions of S-type negative differential resistance (NDR), for both bias polarities and have a number of other features by comparison with diodes based on the --n structures with fused contacts. We discuss the mechanism for the formation of the NDR region of the voltage-current characteristics of the diode.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 54–58, April, 1986.     

Field dependent critical fluctuations aboveT g in the ESR line width of the spin glassAgMn

The ESR of the spin glassAgMn (2.7 and 9.6 at %) has been investigated below and aboveT _g(0.1T _g<T<5T _g) at various microwave frequencies. The analysis yields:1) No explicit frequency dependence but strong magnetic field effects, inherent with ESR-experiments.2) Part of the excess line width is identified as critical spin fluctuations, following a power law. However, because of the presence of the applied field, the reduced temperaturet is not a good scaling variable. We choose the non-linear susceptibility X _s divided byH ², which scales as the order parameter susceptibility. The experiment yieldsW _ex(X _s /H ²) ^p ,p=0.42. From this we deduce z3.     

Mössbauer effect of iodine at pressures to 30 GPa

We report the first high pressure¹²⁹I Mössbauer measurements with elemental iodine at pressures to 30 GPa. A 20 mg/cm^{2 129}I₂ absorber was mounted in a diamond anvil cell with an effective diameter of 0.21 mm. The source used was Mg₃ ^129mTeO₆. Experiments were performed mainly at 4 K and the pressure was monitored by the ruby fluorescence method. With increasing pressure we observe a gradual decrease in ¦e²qQ¦ and an increase in IS and values of the low pressure, molecular phase; at 16 GPa a new phase (HP1) is detected characterized by a change in sign of e²qQ and a smaller value of ¦e²qQ¦, and a substantial increase in . At 24 GPa a new phase (HP2) is formed that is characterized by a smaller value of . In general the population of the molecular phase decreases from 1.0 near 15 GPa to a value of 0.4 at 30 GPa. The fraction of the high pressure phase (HP1 + HP2) increases at the expense of the molecular phase and that of the HP2 at the expense of the HP1 phase. These observations are discussed in relation to the onset of a metallic phase near 16 GPa and recent x-ray diffraction studies.Work performed under the auspices of the U.S. Department of Energy.