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Saint Cloud, MN, United States

Kirmani E.,Saint Cloud State University | Hood C.S.,Illinois Institute of Technology
Journal in Computer Virology | Year: 2010

The traditional approach to modeling of internet worm propagation is to adopt a mathematical model, usually inspired by modeling of the spread of infectious diseases, describing the expected number of hosts infected as a function of the time since the start of infection. The predictions of such a model are then used to evaluate, improve, or develop defense and containment strategies against worms. However, a proper and complete understanding of worm propagation goes well beyond the mathematical formula given by the chosen model for the expected number of hosts infected at a given time. Thus, questions such as fitting the model, assessing the extent to which a specific realization of a worm spread may differ from the model's predictions, behavior of the time points at which infections occur, and the estimation and effects of misspecification of model's parameters must also be considered. In this paper, we address such questions for the well-known random constant spread (RCS) model of worm propagation. We first generalize the RCS model to our nonhomogeneous random scanning (NHRS) model. The NHRS model allows the worm's contact rate to vary during worm propagation and it thus captures far more situations of interest than the RCS model which assumes a scanning rate constant in time. We consider the problem of fitting these models to empirical data and give a simulation procedure for a RCS epidemic. We also show how to obtain a confidence interval for the unknown contact rate in the RCS model. In addition, the use of prior information about the contact rate is discussed. The results and methodologies of this paper illuminate the structure and application of NHRS and RCS models of worm propagation. © Springer-Verlag France 2008. Source

Biswas T.,Saint Cloud State University | Biswas T.,Loyola University New Orleans | Notari A.,University of Heidelberg | Valkenburg W.,RWTH Aachen
Journal of Cosmology and Astroparticle Physics | Year: 2010

In this paper, instead of invoking Dark Energy, we try and fit various cosmological observations with a large Gpc scale under-dense region (Void) which is modeled by a Lemaître-Tolman-Bondi metric that at large distances becomes a homogeneous FLRW metric. We improve on previous analyses by allowing for nonzero overall curvature, accurately computing the distance to the last-scattering surface and the observed scale of the Baryon Acoustic peaks, and investigating important effects that could arise from having nontrivial Void density profiles. We mainly focus on the WMAP 7-yr data (TT and TE), Supernova data (SDSS SN), Hubble constant measurements (HST) and Baryon Acoustic Oscillation data (SDSS and LRG). We find that the inclusion of a nonzero overall curvature drastically improves the goodness of fit of the Void model, bringing it very close to that of a homogeneous universe containing Dark Energy, while by varying the profile one can increase the value of the local Hubble parameter which has been a challenge for these models. We also try to gauge how well our model can fit the large-scale-structure data, but a comprehensive analysis will require the knowledge of perturbations on LTB metrics. The model is consistent with the CMB dipole if the observer is about 15 Mpc off the centre of the Void. Remarkably, such an off-center position may be able to account for the recent anomalous measurements of a large bulk ow from kSZ data. Finally we provide several analytical approximations in different regimes for the LTB metric, and a numerical module for cosmomc, thus allowing for a MCMC exploration of the full parameter space. © 2010 IOP Publishing Ltd and SISSA. Source

Woldeamanuel M.G.,California State University, Northridge | Welle E.,Saint Cloud State University
Studies in Regional Science | Year: 2013

Dependency on the automobile fosters multiple implications such as urban sprawl and negative effects on health and the environment. To help solve automobile dependency, cities need to review their land use patterns and promote new methods for urban and transportation planning. Nevertheless, the pressing question is if cities make transit-oriented changes in regards to development will residents respond accordingly? To investigate answers to this question, this study developed different hypothetical scenarios and gathered residents' reactions. Mode-switching behavior (willingness-to-switch) of the respondents in response to the predefined land use and transportation scenarios was examined using a latent binomial logit model. The analysis results reflected that if dense, mixed and transit-oriented developments are implemented, respondents are likely to switch from car use to other means of transportation. This study also identified public transportation-related factors that persuade respondents to shift from car use to public transportation. Source

Maranto G.,University of Miami | Barton M.,Saint Cloud State University
Computers and Composition | Year: 2010

This article situates current theoretical, rhetorical, and ethical analyses of the net's most prominent social networking sites, MySpace and Facebook. It also discusses the implications of bringing these web sites into the classroom, comparing how students, teachers, and administrators use (and abuse) these spaces. Both MySpace and Facebook privilege a discourse based on the construction and representation of an identity. Rather than assert unique identities, these sites ask users to label and classify themselves according to many criteria, including age, religion, political leanings, hobbies, and interests. Users can then list others who share these labels or interests and request to "add them as friends." MySpace and Facebook emphasize categories and aspects of popular culture that teenagers find important. They remediate the traditions of high school for the Web and by doing so greatly extend their reach. Many writing instructors wonder how these sites can be used to teach writing. How users represent themselves online could help students understand postmodern logics of identity construction and political engagement. However, there are dangers for teachers who create their own profiles and add their students as "friends." Like chat and email, these forums undercut concepts of more conventional rhetorical spaces. They both contribute to and undermine student and faculty ethos, although students may not appreciate that their profiles might have a lasting negative impact. Despite the public nature of most profiles, users often denounce these "invasions" as blatant violations of their privacy. Perhaps teachers and scholars should work to protect the integrity of these spaces. © 2009 Elsevier Inc. All rights reserved. Source

Schoenfuss H.L.,Saint Cloud State University | Maie T.,Clemson University | Moody K.N.,Clemson University | Lesteberg K.E.,Saint Cloud State University | And 2 more authors.
PLoS ONE | Year: 2013

Selective pressures generated by locomotor challenges act at the level of the individual. However, phenotypic variation among individuals that might convey a selective advantage may occur across any of multiple levels of biological organization. In this study, we test for differences in external morphology, muscle mechanical advantage, muscle fiber type and protein expression among individuals of the waterfall climbing Hawaiian fish Sicyopterus stimpsoni collected from sequential pools increasing in elevation within a single freshwater stream. Despite predictions from previous laboratory studies of morphological selection, few directional morphometric changes in body shape were observed at successively higher elevations. Similarly, lever arm ratios associated with the main pelvic sucker, central to climbing ability in this species, did not differ between elevations. However, among climbing muscles, the adductor pelvicus complex (largely responsible for generating pelvic suction during climbing) contained a significantly greater red muscle fiber content at upstream sites. A proteomic analysis of the adductor pelvicus revealed two-fold increases in expression levels for two respiratory chain proteins (NADH:ubiquinone reductase and cytochrome b) that are essential for aerobic respiration among individuals from successively higher elevations. Assessed collectively, these evaluations reveal phenotypic differences at some, but not all levels of biological organization that are likely the result of selective pressures experienced during climbing. © 2013 Schoenfuss et al. Source

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