Long-term planning versus short-term planning in the asymptotical location problem

Given the probability measure $\nu$ over the given region $\Omega\subset \R^n$, we consider the optimal location of a set $\Sigma$ composed by $n$ points \Om in order to minimize the average distance \Sigma\mapsto \int_\Om \dist(x,\Sigma) d\nu (the classical optimal facility location problem). The paper compares two strategies to find optimal configurations: the long-term one which consists in placing all $n$ points at once in an optimal position, and the short-term one which consists in placing the points one by one adding at each step at most one point and preserving the configuration built at previous steps. We show that the respective optimization problems exhibit qualitatively different asymptotic behavior as $n\to\infty$, although the optimization costs in both cases have the same asymptotic orders of vanishing.Comment: for more pictures and some movies as well, see http://www.sissa.it/~brancoli

Statistics of interacting optical solitons

We examine statistics of two interacting optical solitons and describe timing jitter caused by spontaneous emission noise and enhanced by pulse interaction. Dynamics of phase difference is shown to be of crucial importance in determining the probability distribution function (PDF) of the distance between solitons. We find analytically the non-Gaussian tail of the PDF to be exponential. The propagation distance that corresponds to a given bit-error rate is described as a function of system parameters (filtering and noise level), initial distance, and initial phase difference between solitons. We find the interval of parameters where a larger propagation distance can be achieved for higher density of information

Self-consistent Dual Boson approach to single-particle and collective excitations in correlated systems

We propose an efficient dual boson scheme, which extends the DMFT paradigm to collective excitations in correlated systems. The theory is fully self-consistent both on the one- and on the two-particle level, thus describing the formation of collective modes as well as the renormalization of electronic and bosonic spectra on equal footing. The method employs an effective impurity model comprising both fermionic and bosonic hybridization functions. Only single- and two-electron Green's functions of the reference problem enter the theory, due to the optimal choice of the self-consistency condition for the effective bosonic bath. We show that the theory is naturally described by a dual Luttinger-Ward functional and obeys the relevant conservation laws.Comment: 17 pages, 12 figure

Signatures of quantum integrability and nonintegrability in the spectral properties of finite Hamiltonian matrices

For a two-spin model which is (classically) integrable on a five-dimensional hypersurface in six-dimensional parameter space and for which level degeneracies occur exclusively (with one known exception) on four-dimensional manifolds embedded in the integrability hypersurface, we investigate the relations between symmetry, integrability, and the assignment of quantum numbers to eigenstates. We calculate quantum invariants in the form of expectation values for selected operators and monitor their dependence on the Hamiltonian parameters along loops within, without, and across the integrability hypersurface in parameter space. We find clear-cut signatures of integrability and nonintegrability in the observed traces of quantum invariants evaluated in finite-dimensional invariant Hilbert subspaces, The results support the notion that quantum integrability depends on the existence of action operators as constituent elements of the Hamiltonian.Comment: 11 page

Laser beam welding of a low density refractory high entropy alloy

In particular,the effect of different pre-heating temperatures was examined. Due to the low ductility of the material, laser beam welding at room temperature resulted in the formations of hot cracks. Sound butt joints without cracks were produced using pre-heating to T≥600 ◦C. In the initial as-cast condition, the alloy consisted of coarse bcc grains with a small amount of lens-shaped C15 Laves phase particle

Hematological changes in descendants of animals irradiated in different doses

An urgent problem today is not only the study of changes in the stability of the genome of somatic cells, the clarification of the mechanisms of its destabilization under the influence of a complex of environmental factors, including radiation, but also the study of the possibility of hereditary transmission of these changes. In the modern experimental and clinical medicine, the most important problem is the harmful effect of ionizing radiation on the descendants of irradiated parents and the specifics of the effect of radiation on the developing organism. An important aspect of the problem of long-term post-radiation effects is the state of reproductive function and health of the descendants of the irradiated population, due to the physiological characteristics inherent to the mother and child - high sensitivity to the action of ionizing radiation, the consequences of which may manifest after a long period of imaginary well-being. The purpose of the work is to investigate the dynamics of body weight and hematological indiexes in the descendants of intact sexually mature animals and descendants born to animals irradiated at different doses, which were exposed to radiation at a dose of 1.0 Gy. The authors revealed that in descendants born to animals irradiated at different doses, which were exposed to radiation at a dose of 1.0 Gy, it was established that by the 30th day after irradiation at a dose of 1.0 Gy, the general condition of pup rats born from animals irradiated at a dose of 0.5 Gy and exposed to irradiation at a dose of 1.0 Gy is satisfactory against the background of an insignificant decrease in the body weight. This also applies to pup rats born to animals irradiated at a dose of 1.0 Gy, whose general condition slightly improves compared to the previous period of the study. The data obtained showed in the peripheral blood after 1 day in the descendants born to animals irradiated at a dose of 0.5 Gy, after irradiation at a dose of 1.0 Gy, a reduced content of hemoglobin and erythrocytes against the background of an increase in the content of platelets, leukocytes, lymphocytes and reticulocytes in comparison with non-irradiated animals, which was maintained throughout the experiment. Pronounced changes in hematological parameters were observed in the descendants born to animals irradiated at a dose of 1.0 Gy, which were exposed to total γ-irradiation at a dose of 1.0 Gy. The authors suppose their data are in favour of the pronounced adaptationof organisms’ regulatiory systems to ionizing irradiation effect that, firstly, outline the adaptative physiologcal mechanisms and, secondly, show the main launches of pathophysiologcial mechamisns in case of irradiation-induced hematological changes