An algorithm for the maximum revenue jobshop problem

In this paper, we state and study the problem of selecting a product mix and a dispatching rule for a jobshop system to maximize its revenue rate over an infinite planning horizon.     

Heating of ultracold neutrons on beryllium surfaces

The temperature dependence of the loss factor for ultracold neutrons owing to heating at thermal energies on the surface of a beryllium sample is studied. The probability of heating ultracold neutrons is anomalously high throughout the entire measured temperature interval, but especially at low temperatures. Zh. éksp. Teor. Fiz. 114, 786–797 (September 1998)     

A beam summation algorithm for wave radiation and guidance in stratified media

A Gaussian beams summation (GBS) algorithm for tracking source excited wave fields in plane stratified media is presented. In the present application the medium is described by layers with constant gradient of the wave speed, and the GB propagators are calculated recursively in a closed form. The algorithm is calibrated for numerical efficacy and accuracy by defining simple physical criteria for choosing the expansion parameters (the beam collimation and the spectral discretization and truncation) that allow for sparse representation of the source-excited angular spectrum of beams. It is validated for a source-excited example in layered media, where it provides a smooth and physically meaningful solution under multipath and caustic conditions and remains accurate for long propagation ranges where phase error tends to accumulate.     

Photoluminescence of cadmium selenide quantum dots in polymer solutions

The effect of solvent on the photoluminescence of cadmium selenide quantum dots stabilized by oleic acid is examined with the example of two organic solvents: toluene and THF. It is found that THF favors desorption of ligands and formation of surface defects to a greater extent than toluene; as a result, the maximum of the photoluminescence band shifts to the red spectral region and its intensity decreases. The addition of polymers to the solution of quantum dots causes changes in the efficiency of photoluminescence and in the kinetics of its quenching. In the range of low concentrations (≤2 wt %) of quantum dots in polymer solutions, the intensity of luminescence first grows and then passes through a maximum and decreases. This effect may be explained both by the increasing number of surface defects and by quenching via energy transfer to polymers, especially in the case of polymers containing aromatic groups.     

Homeomorphisms of the annulus with a transitive lift

Let f be a homeomorphism of the closed annulus A that preserves the orientation, the boundary components and that has a lift ${\tilde{f}}$ to the infinite strip à which is transitive. We show that, if the rotation numbers of both boundary components of A are strictly positive, then there exists a closed nonempty unbounded set ${B^{-} \subset \tilde{A}}$ such that B ^? is bounded to the right, the projection of B ^? to A is dense, ${B^{-}-(1, 0) \subset B^{-}}$ and ${\tilde{f}(B^{-}) \subset B^{-}}$ . Moreover, if p ₁ is the projection on the first coordinate of Ã, then there exists d > 0 such that, for any ${\tilde z \in B^{-}}$ , $$\limsup_{n\to\infty}\frac{p_1(\tilde f^n(\tilde z))-p_1(\tilde z)}{n}<-d.$$ In particular, using a result of Franks, we show that the rotation set of any homeomorphism of the annulus that preserves orientation, boundary components, which has a transitive lift without fixed points in the boundary is an interval with 0 in its interior.     

Virial scaling corrections to Koopmans' ionization potentials in atoms

Relaxation corrections to Koopmans' approximation for atomic ionization potentials are derived on the basis of the virial theorem. They require no information in addition to that available in the Hartree-Fock computation for the neutral system, and considerably improve the agreement with more accurate ionization potentials.     

Observation of the penetration of subbarrier ultracold neutrons through beryllium foils and coatings

The subbarrier passage of ultracold neutrons through beryllium foils and coatings with a probability much higher than that of tunneling is observed. This effect may be responsible for the so-called anomalous loss of ultracold neutrons. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 5, 317–322 (10 September 1997)     

The use of activation analysis for determination of nutritional balance of declining Pinus halepensis trees in Shaar-Hagai forest

A comprehensive multidisciplinary investigation of the reasons for the decline of Pinus halepensis forests in the Judea mountains in Israel was carried out recently. Mineral content of the pine needles was determined using atomic absorption and neutron activation techniques. A good correlation between these two techniques was obtained. It was found that neutron activation is a very suitable technique for simultaneous determination of numerous elements in biological matter, whenever the facilities of research reactor are available. Manganese content of sick needles was found to be two to three times higher than that of healthy ones, pointing out a possible role of the manganese in the decline of the Pinus halepensis forest.