Screened Coulomb interactions of general macroions with nonzero particle volume

A semianalytical approach is developed to calculate the effective pair potential of rigid arbitrarily shaped macroions with a nonvanishing particle volume, valid within linear screening theory and the mean-field approximation. The essential ingredient for this framework is a mapping of the particle to a singular charge distribution with adjustable effective charge and shape parameters determined by the particle surface electrostatic potential. For charged spheres this method reproduces the well-known Derjaguin-Landau-Verwey-Overbeek (DLVO) potential. Further exemplary benchmarks of the method for more complicated cases, like tori, triaxial ellipsoids, and additive torus-sphere mixtures, leads to accurate closed-form integral expressions for all particle separations and orientations. The findings are relevant for determining the phase behaviour of macroions with experiments and simulations for various particle shapes.Comment: V2: 9 pages, 5 figures; Appendix: 6 pages, 5 figure

Duration of Business Cycles

In this paper the Bry and Boschan (1971) procedure is modified such that it can be applied to quarterly data in order to recalculate the maximum duration of business cycles. In this way it can be shown that the maximum duration of business cycles constitutes 42 quarters in the United States of America and 49 quarters in the United Kingdom. The large difference to the maximum duration of Burns and Mitchell (1946) makes clear that caution is advisable with the application of the filters by Baxter and King (1999) and Christiano and Fitzgerald (2003). If one chooses the maximum duration too low (high), the amplitude of the medium-term business cycles is underestimated (overestimated) and the variability of the growth rate of the long-term trend is overestimated (underestimated).Duration; Business Cycles; Dating Turning Points; Non-Parametric Procedure; Minimum Duration; Maximum Duration; Band-Pass Filter

Sectoral and Industrial Business Cycles

This article calculates the sectoral and industrial business cycles by means of the band-pass filters by Baxter and King (1999) and Christiano and Fitzgerald (2003), to subsequently analyze the correlations between the sectors and industries and the overall economy. It can be shown that the correlations between the business cycles of the sectors and industries and the overall economy differ strongly. The agriculture sector and the industries mining and quarrying, electricity and education for example exhibit almost no correlation with the overall economy; The wholesale and retail as well as the transport industry on the other hand have a high correlation. By means of an analysis of the leading and lagging correlations it can be shown that the wholesale and retail industry leads the overall economy by two quarters. Thus, the wholesale and retail industry can be used as an indicator for the development of the overall economy.Business Cycle; Correlation; Band-Pass Filter; Sectoral Cycles; Industrial Cycles; Cross-Country Correlation; Monetary Policy; Forecasting

Theories of practice and geography

Recent developments in theories of practice have seen place and space taken explicitly into account. In particular, THEODORE SCHATZKI’s ‘site ontology’ offers distinctive but as yet under-explored means of engaging with human geographies. By giving ontological priority to practices as constitutive of the social, this kind of practice theory provides an integrative conceptual framework that enables the analysis of diverse phenomena in relation to each other, over space and time, as they are constituted through practices. This article develops an outline agenda for bringing theories of practice, and particularly SCHATZKI’s ‘site ontology’, together with geographical inquiry. We elucidate this agenda through consideration of three contemporary preoccupations in human geography, comprising emotion, materiality and knowledge

Optical anisotropy induced by ion bombardment of Ag(001)

Grazing incidence ion bombardment results in the formation of nanoripples that induce an anisotropic optical reflection The evolution of the reflectance anisotropy has been monitored in situ with reflectance anisotropy spectroscopy. The Rayleigh-Rice theory (RRT) has been used to analyze the optical spectra quantitatively and provides the evolution of the average ripple period and root-mean-squared surface roughness. After an incipient phase, both the increase in the periodicity and the roughness vary roughly with the square root of the sputter time. Additional high-resolution low-energy electron diffraction (HR-LEED) measurements have been performed to characterize details of the average structure created by ion bombardment

History of Monroe County NY: Town of Sweden & Village of Brockport

History of the Town of Sweden and the Village of Brockport. The text has many details about local people, pioneer history of the area, institutions and their stories. There are also several pages of illustrations of local people and landmark buildings.https://digitalcommons.brockport.edu/local_books/1009/thumbnail.jp

Tuning colloid-interface interactions by salt partitioning

We show that the interaction of an oil-dispersed colloidal particle with an oil-water interface is highly tunable from attractive to repulsive, either by varying the sign of the colloidal charge via charge regulation, or by varying the difference in hydrophilicity between the dissolved cations and anions. In addition, we investigate the yet unexplored interplay between the self-regulated colloidal surface charge distribution with the planar double layer across the oil-water interface and the spherical one around the colloid. Our findings explain recent experiments and have direct relevance for tunable Pickering emulsions.Comment: 5+4 pages, 3+4 figures, V2: improved text and figures, more detailed supplementar

Effective Hamiltonians for holes in antiferromagnets: a new approach to implement forbidden double occupancy

A coherent state representation for the electrons of ordered antiferromagnets is used to derive effective Hamiltonians for the dynamics of holes in such systems. By an appropriate choice of these states, the constraint of forbidden double occupancy can be implemented rigorously. Using these coherent states, one arrives at a path integral representation of the partition function of the systems, from which the effective Hamiltonians can be read off. We apply this method to the t-J model on the square lattice and on the triangular lattice. In the former case, we reproduce the well-known fermion-boson Hamiltonian for a hole in a collinear antiferromagnet. We demonstrate that our method also works for non-collinear antiferromagnets by calculating the spectrum of a hole in the triangular antiferromagnet in the self-consistent Born approximation and by comparing it with numerically exact results.Comment: 9 pages, Latex, 6 figure