How Should a Robot Approach a Pair of People?

This thesis experimentally investigates the comfort of pairs of seated people when they are approached by a robot from different directions. While the effect of robot approach direction on the comfort of a lone person has been investigated previously, the extension to a robot approaching pairs of people has not been explored rigorously. Three maximally-different seating configurations of paired people and eight different robot approach directions were considered. The experiment was augmented with a fourth seating configuration of a lone individual, allowing the responses of grouped and lone participants to be compared. Data obtained from the experiment were analysed using both linear and directional statistics. Results from 180 unique participants showed that the comfort of a person when a robot approached is influenced by the presence and location of a second person. Analysis of these data with directional statistics showed that participant comfort preference clusters into angular regions of ‘suitable for robot approach’ and ‘unsuitable for robot approach’. This finding shows the importance of avoiding robot approach directions of low comfort, rather than selecting a singular robot approach direction of high comfort. Rayleigh’s test of uniformity, a directional statistics method, also shows across all participant configurations that robot approach directions that minimize participant discomfort align spatially with regions that allow for good line of sight of the robot by both people, and are centred on the largest open space that a robot could approach the group from. Participants who were grouped also regarded the robot as having more social agency than did lone experimental participants. Grouped participants were less frustrated with the experimental task and also found it less physically and temporally demanding in comparison to lone experimental participants

Vascular endothelial growth factor can signal through platelet-derived growth factor receptors

Vascular endothelial growth factor (VEGF-A) is a crucial stimulator of vascular cell migration and proliferation. Using bone marrow–derived human adult mesenchymal stem cells (MSCs) that did not express VEGF receptors, we provide evidence that VEGF-A can stimulate platelet-derived growth factor receptors (PDGFRs), thereby regulating MSC migration and proliferation. VEGF-A binds to both PDGFRα and PDGFRβ and induces tyrosine phosphorylation that, when inhibited, results in attenuation of VEGF-A–induced MSC migration and proliferation. This mechanism was also shown to mediate human dermal fibroblast (HDF) migration. VEGF-A/PDGFR signaling has the potential to regulate vascular cell recruitment and proliferation during tissue regeneration and disease

The Sensitivity of Counterfactual Fairness to Unmeasured Confounding

Causal approaches to fairness have seen substantial recent interest, both from the machine learning community and from wider parties interested in ethical prediction algorithms. In no small part, this has been due to the fact that causal models allow one to simultaneously leverage data and expert knowledge to remove discriminatory effects from predictions. However, one of the primary assumptions in causal modeling is that you know the causal graph. This introduces a new opportunity for bias, caused by misspecifying the causal model. One common way for misspecification to occur is via unmeasured confounding: the true causal effect between variables is partially described by unobserved quantities. In this work we design tools to assess the sensitivity of fairness measures to this confounding for the popular class of non-linear additive noise models (ANMs). Specifically, we give a procedure for computing the maximum difference between two counterfactually fair predictors, where one has become biased due to confounding. For the case of bivariate confounding our technique can be swiftly computed via a sequence of closed-form updates. For multivariate confounding we give an algorithm that can be efficiently solved via automatic differentiation. We demonstrate our new sensitivity analysis tools in real-world fairness scenarios to assess the bias arising from confounding.Comment: published at UAI 201

Clustering of obesity-related risk behaviors in children and their mothers

PURPOSE: To examine the clustering and patterns of obesity-related behaviors in children and their mothers and the concordance between mother and child pairs

Cell-matrix biology in vascular tissue engineering

We are developing biocompatible small-calibre vascular substitutes based on polymeric scaffolds that incorporate cell-matrix signals to enhance vascular cell attachment and function. Our graft scaffold comprises an outer electrostatically spun porous polyurethane layer seeded with smooth muscle cells, and a luminal polycaprolactone layer for endothelial cell attachment. Vascular cell adhesion properties of three vascular elastic fibre molecules, tropoelastin, fibrillin-1 and fibulin-5, have been defined, and adhesion fragments optimized. These fragments are being used to coat the scaffolds to enhance luminal endothelial cell attachment, and to regulate smooth muscle cell attachment and function. Tropoelastin-based cell seeding materials are also being developed. In this way, vascular cell-matrix biology is enhancing graft design

Next-to-leading order jet cross sections in polarized hadronic collisions

We present a next-to-leading order computation in QCD of one-jet and two-jet cross sections in polarized hadronic collisions. Our results are obtained in the framework of a general formalism that deals with soft and collinear singularities using the subtraction method. We construct a Monte Carlo program that generates events at the partonic level. We use this code to give phenomenological predictions for $pp$ collisions at $\sqrt{S}=500$ GeV, relevant for the spin physics program at RHIC. The possibility of using jet data to constrain the poorly known polarized parton densities is examined.Comment: 21 pages Latex, uses amssymb.sty and epsfig.sty, 10 ps figures include

On inferring standard deviations from path dependent options

Path dependent option prices are employed to derive implied standard deviations of the underlying security price process without recourse to numerical procedures. We empirically illustrate our methodology by inferring the volatility of gold prices.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25893/1/0000456.pd

An empirical investigation of the EOE gold options market

On April 2, 1981, the European Option Exchange introduced the first organized exchange trading of options on spot gold. We study this new market for three months at its inception and in a parallel period a year later via various tests of rational boundary conditions. Additionally, we use call-put parity to infer implied risk free rates (IRFR's). Deviations of the IRFR's from the prevailing risk free rate permit the possibility of arbitrage through positions known as forward and reverse conversions. Our tests are modified to allow for transaction costs to more fully address the question of market efficiency.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25742/1/0000302.pd