Building up a Sequence of Optimum Media Schedules

A mathematical model is proposed for finding the response to an advertising campaign. Although, hypothetically, there is no restriction on the media involved, the assumptions made are more suited to a campaign in newspapers or magazines, rather than, for example, on television. The deficiencies in the model are discussed, and the use of such a model is compared with the use of simulation techniques. Two previous attempts to optimize similar models are discussed, and a technique for building up a sequence of optimum schedules with an example and a proof of the optimum properties are presented.     

Jets and correlations in large pT reactions

Recent experimental data on correlations in large transverse momentum reactions are analyzed in a two-jet picture. Scaling in jet fragmentation is shown to account well for the existing data. The formulae that are given can be used as a basis for a more detailed analysis of the dynamics. A particular result is that we predict that a two-jet structure can also be produced in events where it is not required that any single hadron has large p_T, with a cross section as large as $\text{1}\text{10}$ mb or more (at ISR energies with the total transverse momentum of each jet ?2.5 GeV/c).     

Ordered steps on Bi(∼ 0001) vicinal surfaces by laser pulse anneal

LEED patterns characteristic of an ordered array of equally spaced steps of minimum height resulted from pulsing disordered Bi(～ 0001) vicinal surfaces. Ten XeCl eximer laser pulses at λ = 308 nm, of 10 ns duration and $\text{4 mJ}\text{cm}{}^2$ each and at 0.5 s intervals optimized ordering on the Bi(101̄16) surface, but additional exposure degraded the surface crystallinity as did a twentyfold increase in power density.     

RPA calculation of the effective charge in a hartree-fock basis

Using a Hartree-Fock basis the diagrams of the Tamm-Dancoff and random-phase approximations have been summed to calculate the effective charge in the (1s0d) shell. The enhancement of the effective charge found by this summation is much less than in an oscillator basis, in fact in most cases the HF RPA result is smaller than the value obtained from the lowest order core polarization diagram in an oscillator basis. The HF neutron effective charges are thus too small. For protons the enhancement of the bare effective charge in a HF basis must also be taken into account, but for cases involving the 0d_5/2 orbital the final result appears rather small.     

Phase transitions and the high temperature expansion for the reggeon calculus

We study a recently proposed lattice version of the reggeon field theory. First a simple one-dimensional system possessing many of the features of the reggeon calculus (Ising model in an imaginary magnetic field) is solved. Surprisingly, the system is found to undergo a phase transition at a non-zero critical temperature, which, although of first order obeys the universality and scaling laws previously postulated for the reggeon calculus. Returning to the full lattice theory, the machinery for performing a high temperature expansion is set up, and initial calculations carried out to order T^?3. In this order, best estimates for the critical indices η and v in the asymptotic elastic amplitude A(s,t) ～ is (ln s)^ηf(t(lns)^v) yield $\text{η = 0 (}\text{1}\text{2}\text{～ 1), v = 0(1}\text{1}\text{2}\text{～ 2)}$. Check on the method, including comparisons with known Ising model results, are also discussed.     

Visualization of the hinge flow in a 5:1 scaled model of the medtronic parallel bileaflet heart valve prosthesis

 In this work, a flow visualization experiment was performed to elucidate features of the retrograde hinge flow through a 5 : 1 scaled model of the Medtronic Parallel bileaflet heart valve. It was hypothesized that this model would provide detailed flow information facilitating identification of flow structures associated with thrombus formation in this valve. The experimental protocol was designed to ensure fluid dynamic similarity between the model and prototype heart valves. Flow was visualized using dye injection. The detailed flow structures observed showed the hinge’s inflow channel was the most suspect region for thrombus formation. Here a complex helical structure was observed. Received: 27 October 1997/Accepted: 1 May 1998