Interactions of large amplitude solitary waves in viscous fluid conduits

The free interface separating an exterior, viscous fluid from an intrusive conduit of buoyant, less viscous fluid is known to support strongly nonlinear solitary waves due to a balance between viscosity-induced dispersion and buoyancy-induced nonlinearity. The overtaking, pairwise interaction of weakly nonlinear solitary waves has been classified theoretically for the Korteweg-de Vries equation and experimentally in the context of shallow water waves, but a theoretical and experimental classification of strongly nonlinear solitary wave interactions is lacking. The interactions of large amplitude solitary waves in viscous fluid conduits, a model physical system for the study of one-dimensional, truly dissipationless, dispersive nonlinear waves, are classified. Using a combined numerical and experimental approach, three classes of nonlinear interaction behavior are identified: purely bimodal, purely unimodal, and a mixed type. The magnitude of the dispersive radiation due to solitary wave interactions is quantified numerically and observed to be beyond the sensitivity of our experiments, suggesting that conduit solitary waves behave as "physical solitons." Experimental data are shown to be in excellent agreement with numerical simulations of the reduced model. Experimental movies are available with the online version of the paper.Comment: 13 pages, 4 figure

Two sides of the ancient vase: eastern and western principles in the works of Keiko Abe

Keiko Abe is recognized as one of the leading marimba virtuosos of the Twentieth century. As a composer, she has been writing for solo marimba since the early 1960s and continues composing for the medium today. Her music became popular with Western percussionists after the publishing of Works for Marimba in 1987. This was her first compilation of works for the five-octave marimba. These pieces have become a constant source of repertoire for collegiate and professional performers. Despite Abe’s popularity and influence, little research has examined her compositions. This document features analysis and background of Abe and her music and is the beginning of this examination. This investigation acknowledges the influence that Eastern and Western musical culture has had in the shaping of Abe’s compositional style. These Eastern and Western cultural influences, and their manifestations in her music, will be identified through analyses of Variations on Japanese Children\u27s Songs (1982), Dream of the Cherry Blossoms (1984), and Marimba d\u27amore (1998). Readers will be presented with the inspiration for these compositions and the Eastern perspectives that invite an authentic performance. These Eastern perspectives include the Japanese concepts that she integrates into formal construction and the historical information behind the traditional Japanese music that is the basis for thematic material. The use of these Eastern elements within a Western approach to form will complete the framework that comprises Abe’s compositional style. Variations on Japanese Children’s Songs and Dream of the Cherry Blossoms will establish how Abe uses these Eastern concepts to construct the form of her compositions. Marimba d’amore will show the progression of her style in the compositional decade following Dream of the Cherry Blossoms. The complete narrative will provide valuable elements of performance practice and establish the compositional formula for one of the first historic figures to compose for the medium of solo marimba

Approximating the {Nash} Social Welfare with Budget-Additive Valuations

We present the first constant-factor approximation algorithm for maximizing the Nash social welfare when allocating indivisible items to agents with budget-additive valuation functions. Budget-additive valuations represent an important class of submodular functions. They have attracted a lot of research interest in recent years due to many interesting applications. For every $\varepsilon > 0$, our algorithm obtains a $(2.404 + \varepsilon)$-approximation in time polynomial in the input size and $1/\varepsilon$. Our algorithm relies on rounding an approximate equilibrium in a linear Fisher market where sellers have earning limits (upper bounds on the amount of money they want to earn) and buyers have utility limits (upper bounds on the amount of utility they want to achieve). In contrast to markets with either earning or utility limits, these markets have not been studied before. They turn out to have fundamentally different properties. Although the existence of equilibria is not guaranteed, we show that the market instances arising from the Nash social welfare problem always have an equilibrium. Further, we show that the set of equilibria is not convex, answering a question of [Cole et al, EC 2017]. We design an FPTAS to compute an approximate equilibrium, a result that may be of independent interest

Resistance Breeding in Apple at Dresden-Pillnitz

Resistance breeding in apple has a long tradition at the Institute of Fruit Breeding now Julius Kuehn-institute in Dresden-Pillnitz. The breeding was aimed at the production of multiple resistance cultivars to allow a more sustainable and environmentally friendly production of apple. In the last decades a series of resistant cultivars (Re®-cultivars) bred in Dresden-Pillnitz has been released, ‘Recolor’ and ‘Rekarda’ in 2006. The main topic in the resistance breeding programme was scab resistance and the donor of scab resistance in most cultivars was Malus x floribunda 821. Due to the development of strains that are able to overcome resistance genes inherited by M. x floribunda 821 and due to the fact that single resistance genes can be broken easily, pyramiding of resistance genes is necessary. Besides scab, fire blight and powdery mildew are the main disease for which a pyramiding of genes is aspired in Pillnitz. Biotechnical approaches are necessary for the early detection of pyramided resistance genes in breeding clones. This paper will give an overview of the resistance breeding of apple in Pillnitz and the methods used