Limits of behavioral control by temporally extended response -reinforcer relations

Three experiments were performed to determine the extent to which the behavior of rats can be controlled by response-reinforcer relations that are extended in time. In Experiment 1, bonus pellets delivered at the end of the session were contingent upon a shift in choice responding within the session. Experiment 2 examined control of aggregated responses by a delayed consequence over a much shorter time period than an entire session. The reinforcing efficacy of bonus pellets was assessed using a chained-schedule procedure. The relation between aggregated responses and a delayed reinforcing consequence was assessed several times per session and with shorter delays than in Experiment 1. Experiment 3 used an adjusting-delay procedure to assess whether differential reinforcer magnitudes have a differential effect on choice behavior when the delay between choice and subsequent reinforcement is equal for the two alternatives. The experiment was designed to determine the longest delay at which differential reinforcement is effective. Taken together, these three experiments were designed to determine the extent to which aggregated responses may be controlled by aggregated reinforcers or a single reinforcing event, and the extent to which a single response may be reinforced by its delayed consequence. Experiment 1 failed to produce reliable control of choice responding by the post-session consequence. Experiment 2 established control of responding by the delayed reinforcer, but such control was reliable for all rats only at delays of 40 s and less. Experiment 3 was unsuccessful in establishing discriminated choice performance by the large reinforcer, even at short delays, preventing the determination of the temporal limit of control by differential reinforcer magnitude. Overall, the results of this series of experiments suggest that the operant behavior of rats can be controlled by delayed consequences, but a finite limit to such control exists. It seems that reinforcers delayed on the order of several minutes or more are unlikely to control the behavior that produces them. Thus, response-reinforcer contiguity determines whether response-reinforcer correlations can control behavior

Nature and the Divine: Classical Greek Philosophy and the Political in the Thought of Leo Strauss and Eric Voegelin.

The following work is an attempt to clarify the relationship of two of the most significant political thinkers of the later part of the twentieth century. Previous scholarship on the relationship between Leo Strauss and Eric Voegelin has focused on the two men\u27s different interpretations of the religious traditions of Judaism and Christianity. In this work, we explore the two men\u27s presentations of classical Greek philosophy to illuminate how their differing readings of the classics come to similar conclusions regarding the nature and limits of the political. Our investigation probes how Strauss\u27s treatment of philosophy as being slightly more comic than tragic and history as being political differs from Voegelin\u27s understanding of philosophy as the successor to tragedy and history as a record of spiritual irruptions. Despite these important differences, both men interpret philosophy as a hopeful search for an elusive ground of order. The structural similarity of both men\u27s understandings of philosophy raises questions whether the differences that are so prominent in the two men\u27s treatment of their respective religious traditions are grounded within the nature of the philosophic enterprise or their different estimates of the vitality of Jewish and Christian worldviews. Strauss\u27s philosophy emphasizes the gap between natural man and the divine and his subsequent need for a divine law, whereas Voegelin focuses on man\u27s need to attune his soul to the divine sources of order in their historic variety and the subsequent spiritual requirement of resisting totalitarian political claims. Both men emphasize a transcendent source of political authority and display a certain amount of skepticism regarding the vessels of the transcendent

Individuals with Peripheral Artery Disease Alter Spatiotemporal Gait Parameters When Walking With Pain versus Without Pain

This abstract compares the spatiotemporal walking parameters of individuals with peripheral artery disease at the time they first begin walking, the time when they first feel pain, and the time when they can no longer continue walking

Harvest of the Month Kits for Early Care and Education Settings

Research tells us that a young child’s food preferences develop within the first few years of life as an infant transitions from eating one food to a multitude of foods with varying flavor profiles.1 With the understanding of a young child’s influential years, early care facilities have the ability to target these young years and help influence dietary preferences in a healthy, engaging, and positive way. For my capstone project, four Harvest of the Month (HOTM) Kits will be created to be used in Early Care and Education settings with three-to-five-year-olds. These HOTM Kits will be correlated with Georgia’s Department of Education’s kindergarten through twelfth grade Harvest of the Month resources. Each kit will combine a locally grown Georgia fruit or vegetable, recipe to prepare the seasonal produce, nutritional activity to tie in learning, children’s literature connection, handout to send home, and a local procurement handout. The goal of these kits are to provide a hands-on learning experience to enhance children’s knowledge of fruits and vegetables through activities and literature connections, allow them an opportunity to try new fruits and vegetables through taste testing, and empower them in the kitchen through recipe creations

A Smartphone-Based Tool for Rapid, Portable, and Automated Wide-Field Retinal Imaging.

Purpose:High-quality, wide-field retinal imaging is a valuable method for screening preventable, vision-threatening diseases of the retina. Smartphone-based retinal cameras hold promise for increasing access to retinal imaging, but variable image quality and restricted field of view can limit their utility. We developed and clinically tested a smartphone-based system that addresses these challenges with automation-assisted imaging. Methods:The system was designed to improve smartphone retinal imaging by combining automated fixation guidance, photomontage, and multicolored illumination with optimized optics, user-tested ergonomics, and touch-screen interface. System performance was evaluated from images of ophthalmic patients taken by nonophthalmic personnel. Two masked ophthalmologists evaluated images for abnormalities and disease severity. Results:The system automatically generated 100° retinal photomontages from five overlapping images in under 1 minute at full resolution (52.3 pixels per retinal degree) fully on-phone, revealing numerous retinal abnormalities. Feasibility of the system for diabetic retinopathy (DR) screening using the retinal photomontages was performed in 71 diabetics by masked graders. DR grade matched perfectly with dilated clinical examination in 55.1% of eyes and within 1 severity level for 85.2% of eyes. For referral-warranted DR, average sensitivity was 93.3% and specificity 56.8%. Conclusions:Automation-assisted imaging produced high-quality, wide-field retinal images that demonstrate the potential of smartphone-based retinal cameras to be used for retinal disease screening. Translational Relevance:Enhancement of smartphone-based retinal imaging through automation and software intelligence holds great promise for increasing the accessibility of retinal screening

Development of High Power Hall Thruster Systems to Enable the NASA Exploration Vision

The next phase of space exploration missions requires high power Solar Electric Propulsion (SEP) systems for large-scale science missions and cargo transportation. Development is underway at Aerojet Rocketdyne on Hall thruster systems that are intended to bracket the needs of future NASA SEP missions in support of space exploration. The Advanced Electric Propulsion System (AEPS) program is developing and qualifying a 13.3kW Hall thruster system to be demonstrated on the Power and Propulsion Element (PPE), which is intended to be the first element of a Lunar Outpost Platform - Gateway (LOP-G). The NextSTEP program is integrating a nested Hall thruster into a 100kW system and testing it for 100 hours. These two programs will provide a path to efficient in-space propulsion that will allow NASA to transfer the large amounts of cargo that is needed to support human missions - first to the moon and then on to Mars. The Advanced Electric Propulsion System (AEPS) program is completing development, qualification and delivery of five flight 13.3kW EP systems to NASA. The flight AEPS system includes a magnetically shielded long-life Hall thruster, Power Processing Unit (PPU) and a Xenon Flow Controller (XFC). The Hall thruster, developed and demonstrated by NASA, operates at input powers up to 12.5kW while providing a specific impulse over an estimated 2800s at an input voltage of 600V. The power processor is designed to accommodate an input voltage range of 95-140V, consistent with operation beyond the orbit of Mars. The integrated system input power is continuously throttleable between 3 and 13.3kW. Component level testing of the EP String has begun with prototype hardware. The NextSTEP program is developing a 100kW Electric Propulsion (EP) system using a nested Hall thruster designed for powers up to 250kW, a modular power processor and a modular mass flow controller. While the program objective is to operate the integrated EP system continuously at 100kW for 100hrs to demonstrate thermal stability and support the development of system life time models, it builds on decades of experience with long-life Hall thrusters and the design is evolvable to a capability of 250kW. Design upgrades that demonstrate the 100kW EP system have been completed and tested. Aerojet Rocketdyne (AR) is excited to support NASA as it extends human reach into deep space and believes that these programs will provide the propulsion to make such missions affordable and sustainable. These systems provide NASA with a range of options to power its deep space transport vehicles. This paper presents the mission requirements for supporting the NASA exploration vision, as well as the status for the high power Hall thruster systems in development