12,728 research outputs found

    UHF flows and the flip automorphism

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    A UHF flow is an infinite tensor product type action of the reals on a UHF algebra AA and the flip automorphism is an automorphism of A⊗AA\otimes A sending x⊗yx\otimes y into y⊗xy\otimes x. If α\alpha is an inner perturbation of a UHF flow on AA, there is a sequence (un)(u_n) of unitaries in A⊗AA\otimes A such that αt⊗αt(un)−un\alpha_t\otimes \alpha_t(u_n)-u_n converges to zero and the flip is the limit of \Ad u_n. We consider here whether the converse holds or not and solve it with an additional assumption: If A⊗A≅AA\otimes A\cong A and α\alpha absorbs any UHF flow β\beta (i.e., α⊗β\alpha\otimes\beta is cocycle conjugate to α\alpha), then the converse holds; in this case α\alpha is what we call a universal UHF flow.Comment: 18 page

    The explanatory relevance of Nash equilibrium: one-dimensional chaos in boundedly rational learning

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    Game theory is often used to explain behavior. Such explanations often proceed by demonstrating that the behavior in question is a Nash equilibrium. Agents are in Nash equilibrium if each agent’s strategy maximizes her payoff given her opponents’ strategies. Nash equilibriums are fundamentally static, but it is usually assumed that equilibriums will be the outcome of a dynamic process of learning or evolution. This article demonstrates that, even in the most simple setting, this need not be true. In two-strategy games with just a single equilibrium, a family of imitative learning dynamics does not lead to equilibrium

    I Want My Middle School Students to Read: Does Using Culturally Relevant Texts Increase Student-Participants’ Engagement Levels Toward Reading Particular Texts?

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    This Dissertation in Practice (DiP) employs an action research methodology to examine the use of the Lived Experience Text (LET) model in an English Language Arts (ELA) classroom in order to increase student-participants‘ overall engagement levels toward reading particular texts. The LET model that the teacher-researcher created is twofold, which consists of student-participants taking part in the selection of their text and the teacher-researcher‘s assessing student-participants to determine if using culturally relevant texts do in fact increase student-participants‘ overall engagement levels toward reading particular texts

    Black Aggie: A Tale of American Folklore

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    Black Aggie: A Tale of American Folklore italic is a musical work written for wind symphony and synthesizer. The piece has the possibility to be performed in two different ways. It can either be performed by a live wind symphony or can be played as an electronic realization with media. The piece was inspired by the legend of Black Aggie - a peculiar grave statue with a series of fantastical stories surrounding her existence. The media presentation is to be played along with the live or synthesized performance. The media consists of photographs and footage of key elements in Black Aggie\u27s legend. All of the media was manipulated with italic Photoshop italic and transferred to the video editing software italic iMovie italic. The realization of the music was created using italic Finale, Logic Pro, italic and italic East West Symphonic Gold italic. The music and the media together create a vivid depiction of Black Aggie\u27s legend

    SHELL BLUFF – A FOSSILIFEROUS RIDGE, THE SITE OF THE EXTINCT OYSTER CRASSOSTREA GIGANTISSIMA AND HISTORY OF ITS IDENTIFICATION

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    Shell Bluff is described by geologists as stratigraphically one of the most important exposures in the Georgia Coastal Plain because the bluff is home to the large oyster, Crassostrea gigantissima, now extinct. Native Americans inhabited this area prior to Hernando DeSoto and his men who visited the area in 1540. They were probably the first Europeans to visit Shell Bluff. John and son William Bartram visited the bluff in 1764 and John described the bluff in his journal and the existence of large oysters. The British naturalist, John Finch, described a fossil oyster taken from the site in 1824 as Ostrea gigantissima, but later named Crassostrea gigantissima. This paper reviews the natural history of the oyster’s identification, and the importance of the oyster and its name

    Search for associations containing young stars (SACY). V. Is multiplicity universal? Tight multiple systems

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    Context: Dynamically undisrupted, young populations of stars are crucial to study the role of multiplicity in relation to star formation. Loose nearby associations provide us with a great sample of close (<<150 pc) Pre-Main Sequence (PMS) stars across the very important age range (≈\approx5-70 Myr) to conduct such research. Aims: We characterize the short period multiplicity fraction of the SACY (Search for Associations Containing Young stars) accounting for any identifiable bias in our techniques and present the role of multiplicity fractions of the SACY sample in the context of star formation. Methods: Using the cross-correlation technique we identified double-lined spectroscopic systems (SB2), in addition to this we computed Radial Velocity (RV) values for our subsample of SACY targets using several epochs of FEROS and UVES data. These values were used to revise the membership of each association then combined with archival data to determine significant RV variations across different data epochs characteristic of multiplicity; single-lined multiple systems (SB1). Results: We identified 7 new multiple systems (SB1s: 5, SB2s: 2). We find no significant difference between the short period multiplicity fraction (FmF_\mathrm{m}) of the SACY sample and that of nearby star forming regions (≈\approx1-2 Myr) and the field (Fm≤F_\mathrm{m}\leq10%) both as a function of age and as a function of primary mass, M1M_1, in the ranges PP [1:200 day] and M2M_2 [0.08 M⊙M_{\odot}-M1 M_1]. Conclusions: Our results are consistent with the picture of universal star formation, when compared to the field and nearby star forming regions (SFRs). We comment on the implications of the relationship between increasing multiplicity fraction with primary mass, within the close companion range, in relation to star formation.Comment: 14 pages, 18 figures, published, A&A http://dx.doi.org/10.1051/0004-6361/20142385

    Using gamma regression for photometric redshifts of survey galaxies

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    Machine learning techniques offer a plethora of opportunities in tackling big data within the astronomical community. We present the set of Generalized Linear Models as a fast alternative for determining photometric redshifts of galaxies, a set of tools not commonly applied within astronomy, despite being widely used in other professions. With this technique, we achieve catastrophic outlier rates of the order of ~1%, that can be achieved in a matter of seconds on large datasets of size ~1,000,000. To make these techniques easily accessible to the astronomical community, we developed a set of libraries and tools that are publicly available.Comment: Refereed Proceeding of "The Universe of Digital Sky Surveys" conference held at the INAF - Observatory of Capodimonte, Naples, on 25th-28th November 2014, to be published in the Astrophysics and Space Science Proceedings, edited by Longo, Napolitano, Marconi, Paolillo, Iodice, 6 pages, and 1 figur

    Monitoring the bio-self-healing performance of cement mortar incubated within soil and water using electrical resistivity

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    In research on self-healing concrete, the restorative performance can be evaluated by a wide range of techniques. However, most of these techniques can be challenging to apply to concrete samples embedded in soil without causing a significant disturbance to the test (as they require removing the samples from the soil, washing off any residue, and examining and returning them). To provide a solution to this issue, we investigated the potential application of an in-situ, non-destructive method utilising electrical resistivity (embedded electrodes). The study was conducted on bio-mortar specimens incubated within saturated soil and water for 11 weeks. The bio-specimens were cast by adding expanded perlite impregnated with Bacillus subtilis and nutrients to the fresh mix. Standard cement mortar (without bacterial agents) was also tested to serve as control specimens. Additional testing (capillary rise and absolute porosity) was conducted under typical conditions to provide context for interpreting the changes in electrical resistivity in relation to the healing process. The bio-mortar showed greater improvements in electrical resistivity (accompanied by a reduction in crack area, water absorption and absolute porosity) than the control mortar. The study demonstrated that the electrical resistivity technique could potentially monitor the self-healing performance of concrete embedded in soil without disturbing the concrete-soil system
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