703 research outputs found

    Teacher Burnout: Locus of Control and its Correlation to Teacher Burnout and Job Satisfaction

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    Teacher burnout is a significant problem in education today. While studies have researched the possible reasons behind it and the effect it has on students and teachers, this study proposed to investigate the correlation between teacher burnout, locus of control and job satisfaction. Surveys were sent to 102 teachers who taught kindergarten through 12th grade in two school districts in Southeastern Ohio. Of the 53 surveys that were returned, 28% of the teachers demonstrated burn out, 40% were dissatisfied with their jobs, and 20% had an external locus of control. There was a moderate correlation between the Rotter IE Scale, which measures locus of control, and the Teacher Burnout Scale. There was no significant relationship between the Rotter IE Scale and the Teacher Job Satisfaction Questionnaire

    Cosmic string Y-junctions: a comparison between field theoretic and Nambu-Goto dynamics

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    We explore the formation of cosmic string Y-junctions when strings of two different types collide, which has recently become important since string theory can yield cosmic strings of distinct types. Using a model containing two types of local U(1) string and stable composites, we simulate the collision of two straight strings and investigate whether the dynamics matches that previously obtained using the Nambu-Goto action, which is not strictly valid close to the junction. We find that the Nambu-Goto action performs only moderately well at predicting when the collision results in the formation of a pair of Y-junctions (with a composite string connecting them). However, we find that when they do form, the late time dynamics matches those of the Nambu-Goto approximation very closely. We also see little radiative emission from the Y-junction system, which suggests that radiative decay due to bridge formation does not appear to be a means via which a cosmological network of such string would rapidly lose energy.Comment: 17 pages, 17 figures; typo correctio

    From: Jim Bevis, Charles A. Shelton, & Rex C. Vermillion

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    CMB power spectra from cosmic strings: predictions for the Planck satellite and beyond

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    We present a significant improvement over our previous calculations of the cosmic string contribution to cosmic microwave background (CMB) power spectra, with particular focus on sub-WMAP angular scales. These smaller scales are relevant for the now-operational Planck satellite and additional sub-orbital CMB projects that have even finer resolutions. We employ larger Abelian Higgs string simulations than before and we additionally model and extrapolate the statistical measures from our simulations to smaller length scales. We then use an efficient means of including the extrapolations into our Einstein-Boltzmann calculations in order to yield accurate results over the multipole range 2 < l 3000 in the case of the temperature power spectrum, which then allows cautious extrapolation to even smaller scales. We find that a string contribution to the temperature power spectrum making up 10% of power at l=10 would be larger than the Silk-damped primary adiabatic contribution for l > 3500. Astrophysical contributions such as the Sunyaev-Zeldovich effect also become important at these scales and will reduce the sensitivity to strings, but these are potentially distinguishable by their frequency-dependence.Comment: 18 pages, 16 figure

    Abelian Higgs Cosmic Strings: Small Scale Structure and Loops

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    Classical lattice simulations of the Abelian Higgs model are used to investigate small scale structure and loop distributions in cosmic string networks. Use of the field theory ensures that the small-scale physics is captured correctly. The results confirm analytic predictions of Polchinski & Rocha [1] for the two-point correlation function of the string tangent vector, with a power law from length scales of order the string core width up to horizon scale with evidence to suggest that the small scale structure builds up from small scales. An analysis of the size distribution of string loops gives a very low number density, of order 1 per horizon volume, in contrast with Nambu-Goto simulations. Further, our loop distribution function does not support the detailed analytic predictions for loop production derived by Dubath et al. [2]. Better agreement to our data is found with a model based on loop fragmentation [3], coupled with a constant rate of energy loss into massive radiation. Our results show a strong energy loss mechanism which allows the string network to scale without gravitational radiation, but which is not due to the production of string width loops. From evidence of small scale structure we argue a partial explanation for the scale separation problem of how energy in the very low frequency modes of the string network is transformed into the very high frequency modes of gauge and Higgs radiation. We propose a picture of string network evolution which reconciles the apparent differences between Nambu-Goto and field theory simulations.Comment: 16 pages, 17 figure

    Geodesic motion in the space-time of cosmic strings interacting via magnetic fields

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    We study the geodesic motion of test particles in the space-time of two Abelian-Higgs strings interacting via their magnetic fields. These bound states of cosmic strings constitute a field theoretical realization of p-q-strings which are predicted by inflationary models rooted in String Theory, e.g. brane inflation. In contrast to previously studied models describing p-q-strings our model possesses a Bogomolnyi-Prasad-Sommerfield (BPS) limit. If cosmic strings exist it would be exciting to detect them by direct observation. We propose that this can be done by the observation of test particle motion in the space-time of these objects. In order to be able to make predictions we have to solve the field equations describing the configuration as well as the geodesic equation numerically. The geodesics can then be classified according to the test particle's energy, angular momentum and momentum along the string axis. We find that the interaction of two Abelian-Higgs strings can lead to the existence of bound orbits that would be absent without the interaction. We also discuss the minimal and maximal radius of orbits and comment on possible applications in the context of gravitational wave emission.Comment: v1: 22 pages including 17 figures; v2: new figure added, section on observables added; acccepted for publication in Phys. Rev.

    CMB power spectrum contribution from cosmic strings using field-evolution simulations of the Abelian Higgs model

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    We present the first field-theoretic calculations of the contribution made by cosmic strings to the temperature power spectrum of the cosmic microwave background (CMB). Unlike previous work, in which strings were modeled as idealized one-dimensional objects, we evolve the simplest example of an underlying field theory containing local U(1) strings, the Abelian Higgs model. Limitations imposed by finite computational volumes are overcome using the scaling property of string networks and a further extrapolation related to the lessening of the string width in comoving coordinates. The strings and their decay products, which are automatically included in the field theory approach, source metric perturbations via their energy-momentum tensor, the unequal-time correlation functions of which are used as input into the CMB calculation phase. These calculations involve the use of a modified version of CMBEASY, with results provided over the full range of relevant scales. We find that the string tension μ\mu required to normalize to the WMAP 3-year data at multipole =10\ell = 10 is Gμ=[2.04±0.06(stat.)±0.12(sys.)]×106G\mu = [2.04\pm0.06\textrm{(stat.)}\pm0.12\textrm{(sys.)}] \times 10^{-6}, where we have quoted statistical and systematic errors separately, and GG is Newton's constant. This is a factor 2-3 higher than values in current circulation.Comment: 23 pages, 14 figures; further optimized figures for 1Mb size limit, appendix added before submission to journal, matches accepted versio

    Interactions of Cosmic Superstrings

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    We develop methods by which cosmic superstring interactions can be studied in detail. These include the reconnection probability and emission of radiation such as gravitons or small string loops. Loop corrections to these are discussed, as well as relationships to (p,q)(p,q)-strings. These tools should allow a phenomenological study of string models in anticipation of upcoming experiments sensitive to cosmic string radiation.Comment: 22 pages, 6 figures; v2: updated reference
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