4,761 research outputs found
Smartphones: Addiction, or Way of Life?
Due to the widespread popularity and seeming dependence on smartphones, especially by millennials and post-millennials, many parents, teachers, and even medical professionals have expressed concern that an entire generation may be addicted to these devices and the various social media to which they provide access. Sociologically, however, it may be more insightful to apply some of the well-established theories related to social change and adaptation to technology, to describe, analyze, and better explain the massive popularity and widespread use of this particular phenomenon as a way of life and its impact on human behavior, social interaction, culture, and society
Sketch-To-Solution: An Exploration of Viscous CFD with Automatic Grids
Numerical simulation of the Reynolds-averaged NavierStokes (RANS) equations has become a critical tool for the design of aerospace vehicles. However, the issues that affect the grid convergence of three dimensional RANS solutions are not completely understood, as documented in the AIAA Drag Prediction Workshop series. Grid adaption methods have the potential for increasing the automation and discretization error control of RANS solutions to impact the aerospace design and certification process. The realization of the CFD Vision 2030 Study includes automated management of errors and uncertainties of physics-based, predictive modeling that can set the stage for ensuring a vehicle is in compliance with a regulation or specification by using analysis without demonstration in flight test (i.e., certification or qualification by analysis). For example, the Cart3D inviscid analysis package has automated Cartesian cut-cell gridding with output-based error control. Fueled by recent advances in the fields of anisotropic grid adaptation, error estimation, and geometry modeling, a similar work flow is explored for viscous CFD simulations; where a CFD application engineer provides geometry, boundary conditions, and flow parameters, and the sketch-to-solution process yields a CFD simulation through automatic, error-based, grid adaptation
A Dangerous Blind Spot in IS Research: False Positives Due to Multicollinearity Combined With Measurement Error
Econometrics textbooks generally conclude that in regression, because the calculation of path estimate variances includes avariance inflation factor (VIF) that reflects correlations between “independent” constructs, multicollinearity should not causefalse positives except in extreme cases. However, textbook treatments of multicollinearity assume perfect measurement –rare in behavioral research. VIF is based on apparent correlations between constructs -- always less than actual correlationswhen measurement error exists. A brief review of recent articles in the MIS Quarterly suggests that the conditions forexcessive false positives are present in published research. In this paper we show (analytically and with a series of MonteCarlo simulations) that multicollinearity combined with measurement error presents greater than expected dangers from falsepositives in IS research when regression or PLS is used. Suggestions for how to address this situation are offered
Improving Estimates of Genetic Maps: A Maximum Likelihood Approach
As a result of previous large, multipoint linkage studies there is a substantial amount of existing marker data. Due to the increased sample size, genetic maps estimated from these data could be more accurate than publicly available maps. However, current methods for map estimation are restricted to data sets containing pedigrees with a small number of individuals, or cannot make full use of marker data that are observed at several loci on members of large, extended pedigrees. In this article, a maximum likelihood (ML) method for map estimation that can make full use of the marker data in a large, multipoint linkage study is described. The method is applied to replicate sets of simulated marker data involving seven linked loci, and pedigree structures based on the real multipoint linkage study of Abkevich et al. (2003, American Journal of Human Genetics 73, 1271–1281). The variance of the ML estimate is accurately estimated, and tests of both simple and composite null hypotheses are performed. An efficient procedure for combining map estimates over data sets is also suggested.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66271/1/j.1541-0420.2006.00532.x.pd
Public Management for the New Millennium: Developing Relevant and Integrated Professional Curricula
The world in which public managers function is rapidly changing and vastly different from that contemplated by the early intellectual stalwarts of public administration. Public agencies are expected to collaborate with each other, with nonprofit organizations and with citizen groups and to use modern technology strategically to manage and deliver services. They are under powerful pressures to use resources efficiently as markets and quasi-markets influenced by global forces play a much greater role in structuring service delivery. Within this context public agencies must manage human resources accordingly, yet also humanely and legally
Dissociation Between Visual Attention and Visual Mental Imagery
Visual mental imagery (which involves generating and transforming visual mental representations, i.e., seeing with the mind's eye) and visual attention appear to be distinct processes. However, some researchers have claimed that imagery effects can be explained by appeal to attention (and thus, that imagery is nothing more than a form of attention). In this study, we used a size manipulation to demonstrate that imagery and attention are distinct processes. We reasoned that if participants are asked to perform each function (imagery and attention) using stimuli of two different sizes (large and small), and that stimulus size affects the two functions differently, then we could conclude that imagery and attention are distinct cognitive processes. Our analyses showed that participants performed the imagery task with greater facility at a large size, whereas attention was performed more easily using smaller stimuli. This finding demonstrates that imagery and attention are distinct cognitive processes.Psycholog
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