The effect of boundary adaptivity on hexagonal ordering and bistability in circularly confined quasi hard discs

The behaviour of materials under spatial confinement is sensitively dependent on the nature of the confining boundaries. In two dimensions, confinement within a hard circular boundary inhibits the hexagonal ordering observed in bulk systems at high density. Using colloidal experiments and Monte Carlo simulations, we investigate two model systems of quasi hard discs under circularly symmetric confinement. The first system employs an adaptive circular boundary, defined experimentally using holographic optical tweezers. We show that deformation of this boundary allows, and indeed is required for, hexagonal ordering in the confined system. The second system employs a circularly symmetric optical potential to confine particles without a physical boundary. We show that, in the absence of a curved wall, near perfect hexagonal ordering is possible. We propose that the degree to which hexagonal ordering is suppressed by a curved boundary is determined by the `strictness' of that wall.Comment: 10 pages, 8 figure

Hyperuniformity of Quasicrystals

Hyperuniform systems, which include crystals, quasicrystals and special disordered systems, have attracted considerable recent attention, but rigorous analyses of the hyperuniformity of quasicrystals have been lacking because the support of the spectral intensity is dense and discontinuous. We employ the integrated spectral intensity, $Z(k)$, to quantitatively characterize the hyperuniformity of quasicrystalline point sets generated by projection methods. The scaling of $Z(k)$ as $k$ tends to zero is computed for one-dimensional quasicrystals and shown to be consistent with independent calculations of the variance, $\sigma^2(R)$, in the number of points contained in an interval of length $2R$. We find that one-dimensional quasicrystals produced by projection from a two-dimensional lattice onto a line of slope $1/\tau$ fall into distinct classes determined by the width of the projection window. For a countable dense set of widths, $Z(k) \sim k^4$; for all others, $Z(k)\sim k^2$. This distinction suggests that measures of hyperuniformity define new classes of quasicrystals in higher dimensions as well.Comment: 12 pages, 14 figure

Climbing depth-bounded adjacent discrepancy search for solving hybrid flow shop scheduling problems with multiprocessor tasks

This paper considers multiprocessor task scheduling in a multistage hybrid flow-shop environment. The problem even in its simplest form is NP-hard in the strong sense. The great deal of interest for this problem, besides its theoretical complexity, is animated by needs of various manufacturing and computing systems. We propose a new approach based on limited discrepancy search to solve the problem. Our method is tested with reference to a proposed lower bound as well as the best-known solutions in literature. Computational results show that the developed approach is efficient in particular for large-size problems

Confined colloidal crystals in and out of equilibrium

Recent studies on confined crystals of charged colloidal particles are reviewed, both in equilibrium and out of equilibrium. We focus in particular on direct comparisons of experiments (light scattering and microscopy) with lattice sum calculations and computer simulations. In equilibrium we address buckling and crystalline multilayering of charged systems in hard and soft slit confinement. We discuss also recent crystalline structures obtained for charged mixtures. Moreover, we put forward possibilities to apply external perturbations, in order to drive the system out of equilibrium. These include electrolyte gradients as well as the application of shear and electric fields.Comment: Review article, 18 pages, 5 figure

Surface-charge-induced freezing of colloidal suspensions

Using grand-canonical Monte Carlo simulations we investigate the impact of charged walls on the crystallization properties of charged colloidal suspensions confined between these walls. The investigations are based on an effective model focussing on the colloids alone. Our results demonstrate that the fluid-wall interaction stemming from charged walls has a crucial impact on the fluid's high-density behavior as compared to the case of uncharged walls. In particular, based on an analysis of in-plane bond order parameters we find surface-charge-induced freezing and melting transitions

The relations between the Ottoman Empire and Bolshevik Russia (1917-1918)

Ankara : The Department of International Relations of Bilkent University, 1998.Thesis (Master's) -- Bilkent University, 1998.Includes bibliographical references leaves 130-139.The fear of being left alone against Russia in an environment of confronting blocs was the main factor behind the decision of the Ottoman government to enter the First World War on the side of the Central Powers. The liberation of the Muslims of Russia from the Russian yoke henceforth became one of the important war objectives of the Ottoman Supreme Command. Nevertheless, the tragic defeat of the Ottoman army in Sankarru~ did not only constitute a serious obstacle against the realization of these aspirations, but it also helped the Russian army to penetrate deep into Ottoman territory. The outbreak of the revolution in Russia and the Bolshevik power seizure in October 1917 provided the Ottoman government with the opportunity of compensating war losses and realizing the strategic aims embodied on the eve and at the beginning of the Great War. The Ottoman government's policy with regard to Russia between 1917-1918 can be analyzed under two main stages. In the short-run the primary aim was the restoration of the pre-war frontier with Russia and acquisition of as much territory in Transcaucasia as possible. With the Russian Treaty of BrestLitovsk, the Ottoman government successfully accomplished its plans with regard to Transcaucasia. In the long-run Ottoman leaders aimed at separating Transcaucasia from Russia in order to create therein independent states that would prevent Russian aggression in the future. In spite of the peace treaty with the Bolsheviks, the Ottoman army continued its military operations in the region. The Ottoman government did everything in its power, militarily or politically, to persuade the Transcaucasian peoples to proclaim their independence. As time went on, Ottomans were not only satisfied with Transcaucasia and North Caucasia was made part of these strategic aims. There were even plans concerning the independence of the Muslims of the Volga basin and Turkestan. Consequently, the primary subject of the relations between the Ottoman and Bolshevik governments in the final two years of the war was the Ottoman activities with regard to the Caucasus region and the Muslims of Russia. These Ottoman objectives not only caused disagreements with the Bolsheviks, but also became a serious source of contention with Germany.Oğuz, C CemM.S