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Search Results: 1 - 10 of 39 matches for " Groff "
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Quasi-Isometries, Boundaries and JSJ-Decompositions of Relatively Hyperbolic Groups
Bradley Groff
Mathematics , 2012,
Abstract: We demonstrate the quasi-isometry invariance of two important geometric structures for relatively hyperbolic groups: the coned space and the cusped space. As applications, we produce a JSJ-decomposition for relatively hyperbolic groups which is invariant under quasi-isometries and outer automorphisms, as well as a related splitting of the quasi-isometry groups of relatively hyperbolic groups.
Towards P = NP via k-SAT: A k-SAT Algorithm Using Linear Algebra on Finite Fields
Matt Groff
Computer Science , 2011,
Abstract: The problem of P vs. NP is very serious, and solutions to the problem can help save lives. This article is an attempt at solving the problem using a computer algorithm. It is presented in a fashion that will hopefully allow for easy understanding for many people and scientists from many diverse fields. In technical terms, a novel method for solving k-SAT is explained. This method is primarily based on linear algebra and finite fields. Evidence is given that this method may require rougly O(n^3) time and space for deterministic models. More specifically the algorithm runs in time O(P V(n+V)^2) with mistaking satisfiable Boolean expressions as unsatisfiable with an approximate probablity 1 / \Theta(V(n+V)^2)^P, where n is the number of clauses and V is the number of variables. It's concluded that significant evidence exists that P=NP. There is a forum devoted to this paper at http://482527.ForumRomanum.com. All are invited to correspond here and help with the analysis of the algorithm. Source code for the associated algorithm can be found at https://sourceforge.net/p/la3sat.
Insights on the Evolution of Religions and Interreligious Dialogue:
Dr. Linda Groff
Rose Croix Journal , 2007,
Abstract: This paper covers many topics relating to the evolution of religions, their interactions (both negative and positive) with each other, and the challenge of finding unity amidst the diversity of the world’s diverse cultural and religious traditions – past, present, and future. Topics covered include: religion as a force for war or peace; a spectrum of possible perspectives within all religions; changing male-female images of divinity in different religions over time; mythology as a link between our outer lives in the world and the inner life of the spirit; how scriptures of all religions support the “golden rule” as well as “peace”; principles for conducting interreligious / interfaith dialogue between peoples of different faiths; the first versus second axial age of the world’s religions; key interfaith organizations and some of their declarations; how to create an interfaith organization within one’s own local community; progress in interfaith dialogue replacing interreligious conflict and war; increasing numbers of people encountering other religions in their spiritual journeys; alternative scenarios (worst case, best case, and most probable case) on the future of religions and their interfaith interactions; and final conclusions
Dynamic Systems Modeling in Educational System Design & Policy
Jennifer Sterling Groff
Journal of New Approaches in Educational Research , 2013, DOI: 10.7821/naer.2.2.72-81
Abstract: Over the last several hundred years, local and national educational systems have evolved from relatively simple systems to incredibly complex, interdependent, policy-laden structures, to which many question their value, effectiveness, and direction they are headed. System Dynamics is a field of analysis used to guide policy and system design in numerous fields including business and urban planning. Applying this tool to educational policy analysis offers insights into the hidden dynamics of the current system, and can be an invaluable tool in designing future scenarios. We explore underlying dynamics of the current US educational system using System Dynamics modeling, and offer an analysis of this tool and its practical application in the US educational system through a case study on the US state of Rhode Island in the 2007-2008 school year.
Modelling Sonoluminescence
Alan Chodos,Sarah Groff
Physics , 1998, DOI: 10.1103/PhysRevE.59.3001
Abstract: In single-bubble sonoluminescence, a bubble trapped by a sound wave in a flask of liquid is forced to expand and contract; exactly once per cycle, the bubble emits a very sharp ($< 50 ps$) pulse of visible light. This is a robust phenomenon observable to the naked eye, yet the mechanism whereby the light is produced is not well understood. One model that has been proposed is that the light is "vacuum radiation" generated by the coupling of the electromagnetic fields to the surface of the bubble. In this paper, we simulate vacuum radiation by solving Maxwell's equations with an additional term that couples the field to the bubble's motion. We show that, in the static case originally considered by Casimir, we reproduce Casimir's result. In a simple purely time-dependent example, we find that an instability occurs and the pulse of radiation grows exponentially. In the more realistic case of spherically-symmetric bubble motion, we again find exponential growth in the context of a small-radius approximation.
“I Don’t See Color”: The Impact of Field Placements on Preservice Teachers’ White Racial Identity Development
Carolyn A. Groff,Terri Peters
Journal of Educational and Developmental Psychology , 2012, DOI: 10.5539/jedp.v2n2p1
Abstract: The purpose of this mixed-method study was to examine the influence of diverse field placements on the White racial identity development of White preservice teachers (n = 92) placed in schools where the student body was either predominantly White or students of color. Using Helms’s theory (1995) of White racial identity development, we selected instruments that measured participants’ awareness of racism, as well as their consciousness about being White (e.g., Color-Blind Racial Attitude Scale and Psychosocial Costs of Racism to Whites Scale). Preservice teachers in nondiverse settings became less aware of racial issues at the end of the field experience. Using pretest scores as covariates, an analysis of covariance indicated that those in more diverse settings had higher levels of White guilt at the end of their field experience. The qualitative results also showed differences in perceptions based on field placements, thus supporting the quantitative findings. Participants were asked how the diversity in their fieldwork placement affected their thoughts about their own ethnic background and social status. For those placed in diverse settings, the most common theme that emerged was the contrast between the characteristics of the students and one’s own family and personal characteristics (e.g., wealth, ethnicity). The results suggest that more than exposure to diverse students is needed to evoke changes in White racial identity in order to prepare preservice teachers to effectively teach students of color.
Fuzzy splicing in precursor-mRNA sequences: prediction of aberrant splice-junctions in viral DNA context  [PDF]
Perambur S. Neelakanta, Sharmistha Chatterjee, Mirjana Pavlovic, Abijit Pandya, Dolores de Groff
Journal of Biomedical Science and Engineering (JBiSE) , 2011, DOI: 10.4236/jbise.2011.44037
Abstract: RNA splicing normally generates stable splice- junction sequences in viruses that are important in the context of virus mimicry. Potential variability in envelop proteins may occur with point-mutations inducing cryptic splice-junctions, which would remain unrecognized by T-memory cells of higher organisms in vaccine trials. Such aberrant splice- junctions result from evolution-specific non-conser- vation of actual splice-junction sites due to mutations; as such, locations of splice-junctions in a test DNA sequence could only be imprecisely specified. Such impreciseness of splice-junction locations (or cryptic sites) in a sequence is evaluated in this study via “noisy” attributes (with associated stochastics) to the mutated subspace; and, relevant fuzzy considerations are invoked with membership attributes expressed in terms of a spatial signal-to-noise ratio (SSNR). That is, SSNR adopted as a membership function expresses the belongingness of a site-region to exon/intron subspaces. An illustrative example with actual (Dengue 1 viral) DNA data is furnished demonstrating the pursuit developed in predicting aberrant splice-junctions at cryptic sites in the test sequence.
Atividade criadora no MST: o acampamento como “ber o da criatividade” = Creative activity in MST: encampment as “cradle of creativity”
Groff, Apoliana Regina,Maheirie, Kátia
Psico , 2011,
Abstract: Este artigo trata de algumas discuss es que foram empreendidas numa pesquisa mais ampla, que teve como objetivo geral compreender a media o da música no MST em Santa Catarina. A pesquisa aconteceu por meio de um estudo em contextos e eventos coletivos neste estado, sendo que os recursos utilizados para constru o das informa es foram a entrevista, o diário de campo e a filmagem. As discuss es neste texto versam sobre a atividade criadora e sobre o acampamento do MST como um contexto de cria o de músicas, de sujeitos e modos de resistir e existir. Em rela o à atividade criadora, est o presentes as contribui es teóricas, principalmente, de Vygotski e Vázquez. As cria es das músicas no MST est o ancoradas, sobretudo, no cotidiano dos Sem Terra, sendo que o acampamento é o contexto onde a maioria das can es é criada. This article approaches some discussions that were undertaken on a larger study, which aimed the general objective of comprehending the mediation of music in MST in Santa Catarina. The research happened through a study in collective contexts and events in this State, and the resources used for the construction of information were the interview, the field diary and filming. The discussions refer to creative activity and to encampment in MST as a context of creation of music, of subjects and ways of resisting and existing. Concerning creative activity, theoretical contributions are presented, mainly from Vygotski and Vázquez. Creations of songs in MST are anchored, above all, to the everyday of the landless, and the encampment is the context where most of the songs are created.
Kalman filtering techniques for focal plane electric field estimation
Tyler D. Groff,N. Jeremy Kasdin
Physics , 2013, DOI: 10.1364/JOSAA.30.000128
Abstract: For a coronagraph to detect faint exoplanets, it will require focal plane wavefront control techniques to continue reaching smaller angular separations and higher contrast levels. These correction algorithms are iterative and the control methods need an estimate of the electric field at the science camera, which requires nearly all of the images taken for the correction. The best way to make such algorithms the least disruptive to science exposures is to reduce the number required to estimate the field. We demonstrate a Kalman filter estimator that uses prior knowledge to create the estimate of the electric field, dramatically reducing the number of exposures required to estimate the image plane electric field while stabilizing the suppression against poor signal-to-noise (SNR). In addition to a significant reduction in exposures, we discuss the relative merit of this algorithm to estimation schemes that do not incorporate prior state estimate history, particularly in regard to estimate error and covariance. Ultimately the filter will lead to an adaptive algorithm which can estimate physical parameters in the laboratory for robustness to variance in the optical train.
Kalman Filter Estimation for Focal Plane Wavefront Correction
Tyler D. Groff,N. Jeremy Kasdin
Physics , 2012, DOI: 10.1117/12.927166
Abstract: Space-based coronagraphs for future earth-like planet detection will require focal plane wavefront control techniques to achieve the necessary contrast levels. These correction algorithms are iterative and the control methods require an estimate of the electric field at the science camera, which requires nearly all of the images taken for the correction. We demonstrate a Kalman filter estimator that uses prior knowledge to create the estimate of the electric field, dramatically reducing the number of exposures required to estimate the image plane electric field. In addition to a significant reduction in exposures, we discuss the relative merit of this algorithm to other estimation schemes, particularly in regard to estimate error and covariance. As part of the reduction in exposures we also discuss a novel approach to generating the diversity required for estimating the field in the image plane. This uses the stroke minimization control algorithm to choose the probe shapes on the deformable mirrors, adding a degree of optimality to the problem and once again reducing the total number of exposures required for correction. Choosing probe shapes has been largely unexplored up to this point and is critical to producing a well posed set of measurements for the estimate. Ultimately the filter will lead to an adaptive algorithm which can estimate physical parameters in the laboratory and optimize estimation.
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