We study the qualitative properties of degenerate diiusion equations used to describe dispersal processes in population dynamics. For systems of interacting populations, the forms of the diiusion models used determine if the population will intermix or remain disjoint (segregated). The dynamics and stability of segregation boundaries between competing populations is analyzed. General population...

Application of logistic regression modeling techniques without subsequent performance analysis regarding predictive ability of the fitted model can result in poorly fitting results that inaccurately predict outcomes on new subjects. Model validation is possibly the most important step in the model building sequence. Model validity refers to the stability and reasonableness of the logistic regre...

We look at how to choose genetic distance so as to maximize the power of detecting spatial structure. We answer this question through analyzing two population genetic models that allow for a spatially structured population in a continuous habitat. These models, like most that incorporate spatial structure, can be characterized by a separation of timescales: the history of the sample can be spli...

  The importance of reliable supply is increasing with supply chain network extension and just-in-time (JIT) production. Just in time implications motivate manufacturers towards single sourcing, which often involves problems with unreliable suppliers. If a single and reliable vendor is not available, manufacturer can split the order among the vendors in order to simultaneously decrease the supp...

Split sex ratio-a pattern where colonies within a population specialize in either male or queen production-is a widespread phenomenon in ants and other social Hymenoptera. It has often been attributed to variation in colony kin structure, which affects the degree of queen-worker conflict over optimal sex allocation. However, recent findings suggest that split sex ratio is a more diverse phenome...

We consider learnability with membership queries in the presence of incomplete information. In the incomplete boundary query model introduced by Blum et al. 7], it is assumed that membership queries on instances near the boundary of the target concept may receive a \don't know" answer. We show that zero{one threshold functions are eeciently learnable in this model. The learning algorithm uses s...

The nematode Caenorhabditis briggsae is a model for comparative developmental evolution with C. elegans. Worldwide collections of C. briggsae have implicated an intriguing history of divergence among genetic groups separated by latitude, or by restricted geography, that is being exploited to dissect the genetic basis to adaptive evolution and reproductive incompatibility; yet, the genomic scope...

Split-and-merge algorithms define a class of image segmentation methods. Topological maps are a mathematical model that represents image subdivisions in 2D and 3D. This paper discusses a split-and-merge method for 3D image data based on the topological map model. This model allows representations of states of segmentations and of merge and split operations. Indeed, it can be used as data struct...