A comprehensive study of personal and social information use in female brown-headed cowbirds, Molothrus ater

Brood parasites face considerable cognitive challenges when locating and selecting host nests for their young. One aspect of this challenge is determining how to use different sources of information to make decisions regarding the quality of a prospective nest. Here we investigate how female-brown-headed cowbirds, Molothrus ater, use information when prospecting for nests, and then expand upon this to investigate decisions related to foraging. In chapter 1, we demonstrated female could use social information acquired from observing the nest prospecting patterns of conspecifics to influence their own patterns of nest selection. Furthermore, we found a negative relationship between a female’s accuracy at using personal information and her tendency to copy others. In chapter 2, we found the females were able to use social information in a foraging setting as well. The female’s accuracy using personal information remained consistent across nest prospecting and foraging contexts however, the relationship between accuracy and tendency to copy others drastically reversed. A follow up experiment revealed the likely possibility that the differing relationship between personal and social information use depended on the degree of conflict that existed between the two types of information. In chapter 3, we redeveloped and implemented a new RFID tracking technology allowing us to investigate how the cognitive strategies from chapters 1 and 2 translated to a naturalistic, socially complex breeding environment. We found female cowbirds who spent more time prospecting, produced a greater quantity of eggs and demonstrated high accuracy scores during chapter 1 and 2, whereas females who relied on copying others spent significantly less time prospecting and demonstrated lower laying accuracy scores. By demonstrating how individuals’ cognitive strategies relate across context and translate to a socially complex setting, we have demonstrated the importance of examining behaviour in both of these settings and our RFID tracking technology provides researchers with the framework to effectively study this in the future

Network Reconstruction from Intrinsic Noise

This paper considers the problem of inferring an unknown network of dynamical systems driven by unknown, intrinsic, noise inputs. Equivalently we seek to identify direct causal dependencies among manifest variables only from observations of these variables. For linear, time-invariant systems of minimal order, we characterise under what conditions this problem is well posed. We first show that if the transfer matrix from the inputs to manifest states is minimum phase, this problem has a unique solution irrespective of the network topology. This is equivalent to there being only one valid spectral factor (up to a choice of signs of the inputs) of the output spectral density. If the assumption of phase-minimality is relaxed, we show that the problem is characterised by a single Algebraic Riccati Equation (ARE), of dimension determined by the number of latent states. The number of solutions to this ARE is an upper bound on the number of solutions for the network. We give necessary and sufficient conditions for any two dynamical networks to have equal output spectral density, which can be used to construct all equivalent networks. Extensive simulations quantify the number of solutions for a range of problem sizes. For a slightly simpler case, we also provide an algorithm to construct all equivalent networks from the output spectral density.Comment: 11 pages, submitted to IEEE Transactions on Automatic Contro

Robust Network Reconstruction in Polynomial Time

This paper presents an efficient algorithm for robust network reconstruction of Linear Time-Invariant (LTI) systems in the presence of noise, estimation errors and unmodelled nonlinearities. The method here builds on previous work on robust reconstruction to provide a practical implementation with polynomial computational complexity. Following the same experimental protocol, the algorithm obtains a set of structurally-related candidate solutions spanning every level of sparsity. We prove the existence of a magnitude bound on the noise, which if satisfied, guarantees that one of these structures is the correct solution. A problem-specific model-selection procedure then selects a single solution from this set and provides a measure of confidence in that solution. Extensive simulations quantify the expected performance for different levels of noise and show that significantly more noise can be tolerated in comparison to the original method.Comment: 8 pages, to appear in 51st IEEE Conference on Decision and Contro

Price Dispersion and Accessibility: A Case study of Fast Food

This study examines spatial variation in the price and accessibility of fast food across a major urban area. We use novel data on the price of a representative fast food meal and the location of fast food restaurants belonging to one of three major chains in the District of Columbia and its surrounding suburbs. These data are used to test a structural model of spatial competition. The results of this study are easily interpreted and compared with a past analysis. We find that spatial differences in costs and demand conditions drive variation in the number of firms operating in a market, which in turn affects prices.food prices, food accessibility, spatial competition, price dispersion, fast food

Leggett-Garg inequalities and the geometry of the cut polytope

The Bell and Leggett-Garg tests offer operational ways to demonstrate that non-classical behavior manifests itself in quantum systems, and experimentalists have implemented these protocols to show that classical worldviews such as local realism and macrorealism are false, respectively. Previous theoretical research has exposed important connections between more general Bell inequalities and polyhedral combinatorics. We show here that general Leggett-Garg inequalities are closely related to the cut polytope of the complete graph, a geometric object well-studied in combinatorics. Building on that connection, we offer a family of Leggett-Garg inequalities that are not trivial combinations of the most basic Leggett-Garg inequalities. We then show that violations of macrorealism can occur in surprising ways, by giving an example of a quantum system that violates the new "pentagon" Leggett-Garg inequality but does not violate any of the basic "triangle" Leggett-Garg inequalities.Comment: 5 pages, 1 figur