Animal Cognition: Monkey Meteorology

Mangabey monkeys have been shown to rely on memory of recent trends in temperature and solar radiation to decide whether to feed on a particular patch of fruit. These observations reveal a rich mental representation of the physical environment in monkeys and suggest foraging may have been an important selective pressure in primate cognitive evolution

Design Environment for Multifidelity and Multidisciplinary Components

One of the greatest challenges when developing propulsion systems is predicting the interacting effects between the fluid loads, thermal loads, and structural deflection. The interactions between technical disciplines often are not fully analyzed, and the analysis in one discipline often uses a simplified representation of other disciplines as an input or boundary condition. For example, the fluid forces in an engine generate static and dynamic rotor deflection, but the forces themselves are dependent on the rotor position and its orbit. It is important to consider the interaction between the physical phenomena where the outcome of each analysis is heavily dependent on the inputs (e.g., changes in flow due to deflection, changes in deflection due to fluid forces). A rigid design process also lacks the flexibility to employ multiple levels of fidelity in the analysis of each of the components. This project developed and validated an innovative design environment that has the flexibility to simultaneously analyze multiple disciplines and multiple components with multiple levels of model fidelity. Using NASA's open-source multidisciplinary design analysis and optimization (OpenMDAO) framework, this multifaceted system will provide substantially superior capabilities to current design tools

A Physiologically-Inspired Model of Numerical Classification Based on Graded Stimulus Coding

In most natural decision contexts, the process of selecting among competing actions takes place in the presence of informative, but potentially ambiguous, stimuli. Decisions about magnitudes – quantities like time, length, and brightness that are linearly ordered – constitute an important subclass of such decisions. It has long been known that perceptual judgments about such quantities obey Weber's Law, wherein the just-noticeable difference in a magnitude is proportional to the magnitude itself. Current physiologically inspired models of numerical classification assume discriminations are made via a labeled line code of neurons selectively tuned for numerosity, a pattern observed in the firing rates of neurons in the ventral intraparietal area (VIP) of the macaque. By contrast, neurons in the contiguous lateral intraparietal area (LIP) signal numerosity in a graded fashion, suggesting the possibility that numerical classification could be achieved in the absence of neurons tuned for number. Here, we consider the performance of a decision model based on this analog coding scheme in a paradigmatic discrimination task – numerosity bisection. We demonstrate that a basic two-neuron classifier model, derived from experimentally measured monotonic responses of LIP neurons, is sufficient to reproduce the numerosity bisection behavior of monkeys, and that the threshold of the classifier can be set by reward maximization via a simple learning rule. In addition, our model predicts deviations from Weber Law scaling of choice behavior at high numerosity. Together, these results suggest both a generic neuronal framework for magnitude-based decisions and a role for reward contingency in the classification of such stimuli

Full Lyapunov Exponent Placement in Reentry Trajectories

This study investigated the ability to control the chaotic reentry of a Delta-Clipper like vehicle by setting the values of initial arid final principal dynamical directions as well as the Lyapunov exponents. A model of the original controlled reentry vehicle was created through the use of the equations of motion in conjunction with an atmospheric model. A modified linear quadratic regulator allowed the set up of a boundary value problem which specified the Lyapunov exponents and determined the gain matrix as a function of time. The gain matrix can eventually be used in the control system of the vehicle

Master of Science

thesisA research study was conducted for the Utah Department of Transportation regarding settlement caused by embankment construction for a new bridge located about V mile east of the Interstate 15-State Route 77 interchange in Springville, Utah. Embankment ramps were about 425-ft long, 106-ft wide, and 30-ft tall at the highest points, with vertical side slopes supported by mechanically stabilized earth (MSE) walls. The primary objectives of this study were as follows: (1) Determine consolidation properties of the cohesive soils; (2) predict time rate of primary consolidation settlement using numerical analyses; (3) compare measured rates of primary consolidation settlement with predicted values; and (4) compare the effectiveness of Asaoka's (1978) method for predicting the time for surcharge removal with more advanced methods. These objectives were attained by performing field and laboratory investigations to determine properties of the soils at the site, installing instrumentation to measure settlement and other relevant parameters, and performing numerical analyses to predict the rate of primary consolidation settlement within each cohesive layer. During the field investigation, undisturbed piston samples were obtained and standard penetration, cone penetration, and vane shear tests were performed. Instruments installed to monitor soil behavior included nineteen piezometers, twenty spider magnets, six settlement manometers, three push-in cells, two ShapeAccelArrays, one vertical inclinometer, one horizontal inclinometer, three pressure cells for vertical stress, and three pressure cells for horizontal stress. The laboratory investigation included classification and constant rate of strain consolidation tests. Primary consolidation settlement was predicted using Terzaghi's (1947) and Davis and Raymond's (1965) one-dimensional consolidation theories in conjunction with the finite difference method. Results from these two analyses were compared with measured primary consolidation settlement data obtained from field instruments. Primary consolidation settlement results using both methods proved to be reasonable, but no conclusion could be reached regarding which method yielded better predictions. Predicted times for surcharge removal analyzed using Asaoka's method based on measured values of surface settlement were incorrect because of the erroneous assumption that the underlying soil is homogenous. Better estimates of time for surcharge removal were obtained by analyzing each of the cohesive layers separately

Far apart but closer together:a quantitative and qualitative analysis of the career structure and organisational culture of the post-war British Diplomatic Service

A good deal has been written about the organisation and structure of the British diplomatic establishment since 1945. This paper seeks to use detailed quantitative and qualitative data to help develop an understanding of the background and career trajectories of the most senior figures in the Diplomatic Service in 1975. By tracing their careers it is possible to identify more precisely than before the changing educational and social background of these individuals when compared with previous generations of diplomats. The paper also examines certain core features of the culture of the diplomatic establishment during the post-war decades, analysing how it both shaped and was shaped by particular structures and practices. The paper argues that, despite the existence of a peripatetic career structure that dispersed members of the diplomatic establishment around the globe, there were still numerous opportunities for the kinds of personal contact necessary to maintain an integrated cultur

Vicarious Reinforcement in Rhesus Macaques (Macaca Mulatta)

What happens to others profoundly influences our own behavior. Such other-regarding outcomes can drive observational learning, as well as motivate cooperation, charity, empathy, and even spite. Vicarious reinforcement may serve as one of the critical mechanisms mediating the influence of other-regarding outcomes on behavior and decision-making in groups. Here we show that rhesus macaques spontaneously derive vicarious reinforcement from observing rewards given to another monkey, and that this reinforcement can motivate them to subsequently deliver or withhold rewards from the other animal. We exploited Pavlovian and instrumental conditioning to associate rewards to self (M1) and/or rewards to another monkey (M2) with visual cues. M1s made more errors in the instrumental trials when cues predicted reward to M2 compared to when cues predicted reward to M1, but made even more errors when cues predicted reward to no one. In subsequent preference tests between pairs of conditioned cues, M1s preferred cues paired with reward to M2 over cues paired with reward to no one. By contrast, M1s preferred cues paired with reward to self over cues paired with reward to both monkeys simultaneously. Rates of attention to M2 strongly predicted the strength and valence of vicarious reinforcement. These patterns of behavior, which were absent in non-social control trials, are consistent with vicarious reinforcement based upon sensitivity to observed, or counterfactual, outcomes with respect to another individual. Vicarious reward may play a critical role in shaping cooperation and competition, as well as motivating observational learning and group coordination in rhesus macaques, much as it does in humans. We propose that vicarious reinforcement signals mediate these behaviors via homologous neural circuits involved in reinforcement learning and decision-making