We study a capacitated network design problem in geometric setting. We assume that the input consists of an integral link capacity k and two sets of points on a plane, sources and sinks, each source/sink having an associated integral demand (amount of flow to be shipped from/to). The capacitated geometric network design problem is to construct a minimum-length network N that allows to route the...

We study the minimum concave cost flow problem over a two-dimensional grid network (CFG), where one dimension represents time periods and the other dimension represents echelons. The concave function over each arc is given by a value oracle. We give a characterization of the computational complexity of CFG based on the grid size (T periods and L echelons), the distribution of sources and sinks ...

The paired source and sink concepts are used increasingly in ecology and Earth sciences, but they have evolved in divergent directions, hampering communication across disciplines. We propose a conceptual framework that unifies existing definitions, and review their most significant consequences for the various disciplines. A general definition of the source and sink concepts that transcends dis...

Quantitative tests of historical hypotheses are necessary to advance our understanding of biogeographic patterns of species distributions, but direct tests are often hampered by incomplete fossil or historical records. Here we present an alternative approach in which we develop a dynamic model that allows us to test hypotheses about regional rates of taxon origination, extinction, and dispersal...

With widespread, long-term historical use of plastics and the presence microplastics in a range new existing products, there is rising concern about their potential impacts on freshwater ecosystems. Understanding how are transported distributed along river systems key to assessing impacts. Modelling main flow dynamics, mixing, sedimentation resuspension processes essential for an understanding ...

Abstract. On Arctic sea ice, the melt of snow and ice generate a summertime flux fresh water to upper ocean. The partitioning this meltwater storage in ponds deposition ocean has consequences for surface heat budget, mass balance, primary productivity. Synthesizing results from 1997–1998 SHEBA field experiment, we calculate sources sinks produced on multiyear floe during summer melt. total inpu...