4,347 research outputs found
From white elephant to Nobel Prize: Dennis Gabor’s wavefront reconstruction
Dennis Gabor devised a new concept for optical imaging in 1947 that went by a variety of names over the following decade: holoscopy, wavefront reconstruction, interference microscopy, diffraction microscopy and Gaboroscopy. A well-connected and creative research engineer, Gabor worked actively to publicize and exploit his concept, but the scheme failed to capture the interest of many researchers. Gabor’s theory was repeatedly deemed unintuitive and baffling; the technique was appraised by his contemporaries to be of dubious practicality and, at best, constrained to a narrow branch of science. By the late 1950s, Gabor’s subject had been assessed by its handful of practitioners to be a white elephant. Nevertheless, the concept was later rehabilitated by the research of Emmett Leith and Juris Upatnieks at the University of Michigan, and Yury Denisyuk at the Vavilov Institute in Leningrad. What had been judged a failure was recast as a success: evaluations of Gabor’s work were transformed during the 1960s, when it was represented as the foundation on which to construct the new and distinctly different subject of holography, a re-evaluation that gained the Nobel Prize for Physics for Gabor alone in 1971. This paper focuses on the difficulties experienced in constructing a meaningful subject, a practical application and a viable technical community from Gabor’s ideas during the decade 1947-1957
Effectiveness of Hybrid Learning Environments
Hybrid learning environment (HLE) is a classroom- and computer-based environment that is an open system, allowing synchronous and asynchronous interactions and encounters with other participants. This paper assesses the learning effectiveness of students in HLE for two core MSIS courses at DSU. In conclusion, the results attest to the viability of HLE. In-class and video conferencing students get to benefit from the virtual classroom setting (supporting web-site, asynchronous communication via electronic discussion board and email, and the opportunity to review the recorded class), while Internet students get to benefit by reducing the anxiety and feeling of isolation through the opportunity to feel and experience the classroom setting. HLE affords alternative delivery mechanisms, thereby accommodating various learning models
Altered functional and structural brain network organization in autism.
Structural and functional underconnectivity have been reported for multiple brain regions, functional systems, and white matter tracts in individuals with autism spectrum disorders (ASD). Although recent developments in complex network analysis have established that the brain is a modular network exhibiting small-world properties, network level organization has not been carefully examined in ASD. Here we used resting-state functional MRI (n = 42 ASD, n = 37 typically developing; TD) to show that children and adolescents with ASD display reduced short and long-range connectivity within functional systems (i.e., reduced functional integration) and stronger connectivity between functional systems (i.e., reduced functional segregation), particularly in default and higher-order visual regions. Using graph theoretical methods, we show that pairwise group differences in functional connectivity are reflected in network level reductions in modularity and clustering (local efficiency), but shorter characteristic path lengths (higher global efficiency). Structural networks, generated from diffusion tensor MRI derived fiber tracts (n = 51 ASD, n = 43 TD), displayed lower levels of white matter integrity yet higher numbers of fibers. TD and ASD individuals exhibited similar levels of correlation between raw measures of structural and functional connectivity (n = 35 ASD, n = 35 TD). However, a principal component analysis combining structural and functional network properties revealed that the balance of local and global efficiency between structural and functional networks was reduced in ASD, positively correlated with age, and inversely correlated with ASD symptom severity. Overall, our findings suggest that modeling the brain as a complex network will be highly informative in unraveling the biological basis of ASD and other neuropsychiatric disorders
A Climate Action Plan for Bucknell University
The accelerating pace of human-influenced climate change and our growing awareness of its negative public-health, environmental, and economic consequences compel decisive action. In recent years, many institutions of higher education have taken leadership roles to promote sustainability and climate neutrality at the campus level. In January 2008, Bucknell University became a signatory to the American Colleges and University Presidents Climate Commitment (ACUPCC). Under this agreement, Bucknell is required to prepare a comprehensive inventory of greenhouse gas emissions by May 2009, to update the inventory every other year thereafter, and to implement tangible emissions-reducing actions in the short-term (two years). The ACUPCC further requires Bucknell to develop a long-term Climate Action Plan (CAP) by May 2010 containing.
This Climate Action Plan is in response to being a signatory to ACUPCC. The Plan provides an overview of Bucknell University\u27s greenhouse gas emissions and provides recommendations for reducing them. The plan was developed by the Campus Greening Council, with leadership from the Bucknell University Environmental Center and the Facilities Department
Teaching IT in a Hybrid Learning Environment: A case study
Dakota State University offers a Master’s degree in Information Systems to students using what is referred to as a hybrid learning environment, a simultaneous combination of in-class, remote interactive audio/video connections (DDN), and Internet connections. This paper identifies some of the issues and challenges that have been encountered by faculty and students in this teaching environment
A review of nuclear thermal propulsion carbide fuel corrosion and key issues
Corrosion (mass loss) of carbide nuclear fuels due to their exposure to hot hydrogen in nuclear thermal propulsion engine systems greatly impacts the performance, thrust-to-weight and life of such systems. This report provides an overview of key issues and processes associated with the corrosion of carbide materials. Additionally, past pertinent development reactor test observations, as well as related experimental work and analysis modeling efforts are reviewed. At the conclusion, recommendations are presented, which provide the foundation for future corrosion modeling and verification efforts
Should online retailers emphasize efficiency or experience? First insights on the evolution and heterogeneity of website attributes
Anecdotal evidence indicates a notable shift in online consumer expectations, emphasizing a desire for an enjoyable online shopping experience, beyond convenience and efficiency. This insight thus prompts key questions: Should retailers emphasize efficiency-related or experience-related website attributes, and in which contexts might one priority be superior to the other for encouraging consumer loyalty? The present study provides initial insights into the evolution of the effectiveness of different website attributes and heterogeneity in their effects. Using a rich data set, spanning vastly different contexts and time periods, the authors detect new, evolving patterns by which different website attributes relate to customer loyalty. Experience-related attributes have become more important than efficiency-related attributes in recent years, with some noteworthy contingencies, such that they are especially impactful for services (vs. products) and in cultures with long-term (vs. short-term), high (vs. low) self-indulgence, and high (vs. low) masculinity orientations. The increasing importance of experience-related attributes is driven by cultures with a low (vs. high) uncertainty avoidance. These insights in turn offer practical implications for retailers navigating the challenges associated with designing their websites to drive customer loyalty
A Survey of Systems Engineering Effectiveness - Initial Results
This survey quantifies the relationship between the application of Systems Engineering (SE) best practices to projects and programs, and the performance of those projects and programs. The survey population consisted of projects and programs executed by defense contractors who are members of the Systems Engineering Division (SED) of the National Defense Industrial Association (NDIA). The deployment of SE practices on a project or program was measured through the availability and characteristics of specific SE-related work products. Project Performance was measured through typically available project measures of cost performance, schedule performance, and scope performance. Additional project and program information such as project size, project domain, and other data was also collected to aid in characterizing the respondent's project. Analysis of the survey responses revealed moderately strong statistical relationships between Project Performance and several categorizations of specific of SE best practices. Notably stronger relationships are apparent by combining the effects of more than one the best practices categories. Of course, Systems Engineering Capability alone does not ensure outstanding Project Performance. The survey results show notable differences in the relationship between SE best practices and performance between more challenging as compared to less challenging projects. The statistical relationship between Project Performance and the combination of SE Capability and Project Challenge is quite strong for survey data of this type
Formal Verification of Autonomous Vehicle Platooning
The coordination of multiple autonomous vehicles into convoys or platoons is expected on our highways in the near future. However, before such platoons can be deployed, the new autonomous behaviors of the vehicles in these platoons must be certified. An appropriate representation for vehicle platooning is as a multi-agent system in which each agent captures the "autonomous decisions" carried out by each vehicle. In order to ensure that these autonomous decision-making agents in vehicle platoons never violate safety requirements, we use formal verification. However, as the formal verification technique used to verify the agent code does not scale to the full system and as the global verification technique does not capture the essential verification of autonomous behavior, we use a combination of the two approaches. This mixed strategy allows us to verify safety requirements not only of a model of the system, but of the actual agent code used to program the autonomous vehicles
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