975 research outputs found
Non-singular inflationary universe from polymer matter
We consider a polymer quantization of a free massless scalar field in a
homogeneous and isotropic cosmological spacetime. This quantization method
assumes that field translations are fundamentally discrete, and is related to
but distinct from that used in loop quantum gravity. The semi-classical
Friedman equation yields a universe that is non-singular and non-bouncing,
without quantum gravity. The model has an early de Sitter-like inflationary
phase with sufficient expansion to resolve the horizon and entropy problems,
and a built in mechanism for a graceful exit from inflation.Comment: 4 pages, 1 figure; v2 clarifications added, reference update
A Large Class Engagement (LCE) Model Based on Service-Dominant Logic (SDL) and Flipped Classrooms
Ensuring that university graduates are ready for their professional futures is a complex undertaking that includes, but is not limited to, the development of their professional knowledge and skills, and the provision of empowering learning experiences established through their own contributions. One way to draw these complex processes together for a large undergraduate class setting may be through a teaching and learning framework that centres on engagement. Engagement precipitates deeper learning, based on student-centred knowledge and skills development through co-creation. This conceptual paper proposes the Large Class Engagement model (LCE), which integrates high levels of student cognitive involvement and participation as antecedents to engagement, and treats engagement as a co-creation process between educators and students. The model applies services theory to conceptualise engagement in large flipped classes. The case study in this paper adds a new perspective to higher education. More specifically, it illustrates how a service dominant logic can be used to foster co-creation and thus enhance the learning experiences and outcomes in very large classes
A Cross-Cultural Study of American and Russian Proprieties in Communication
An examination of eleven intercultural textbooks, used in the field of communication in America, reveals little research comparing Russian and American proprieties in communication (Chen & Starosta, 1998; Dodd, 1998; Jandt, 2004a; Jandt, 2004b; Kelly, Laffoon & McKerrow, 1994; Lustig & Koester, 1996; Martin & Nakayama, 2004; Martin & Nakayama, 2005; Martin, Nakayama & Flores, 2002; Samovar & Porter, 2003; Samovar & Porter, 2001). In order to investigate the similarities and differences (S/D) of the two countries, an instrument was developed containing questions dealing with proprieties and customs appropriate in both cultural settings. In order to maintain language integrity, the 29-item instrument was administered to English speaking students with: 1) no direct exposure to the Russian culture, or 2) direct exposure to the Russian culture. The results suggest proprieties in American and Russian society are more similar than difference in the majority of areas investigated in this research. However, there was a substantial difference between the two cultures in the following four areas: a) Russians are less likely than Americans to discuss their ethnicity in public situations; b) Russians are more polite than Americans in social situations; c) Russians feel more comfortable than Americans about speaking their minds in public situations; d) Russians are more honest when expressing opinions than their American counterparts
In defense of the epistemic view of quantum states: a toy theory
We present a toy theory that is based on a simple principle: the number of
questions about the physical state of a system that are answered must always be
equal to the number that are unanswered in a state of maximal knowledge. A wide
variety of quantum phenomena are found to have analogues within this toy
theory. Such phenomena include: the noncommutativity of measurements,
interference, the multiplicity of convex decompositions of a mixed state, the
impossibility of discriminating nonorthogonal states, the impossibility of a
universal state inverter, the distinction between bi-partite and tri-partite
entanglement, the monogamy of pure entanglement, no cloning, no broadcasting,
remote steering, teleportation, dense coding, mutually unbiased bases, and many
others. The diversity and quality of these analogies is taken as evidence for
the view that quantum states are states of incomplete knowledge rather than
states of reality. A consideration of the phenomena that the toy theory fails
to reproduce, notably, violations of Bell inequalities and the existence of a
Kochen-Specker theorem, provides clues for how to proceed with this research
program.Comment: 32 pages, REVTEX, based on a talk given at the Rob Clifton Memorial
Conference, College Park, May 2003; v2: minor modifications throughout,
updated reference
Non-local Correlations are Generic in Infinite-Dimensional Bipartite Systems
It was recently shown that the nonseparable density operators for a bipartite
system are trace norm dense if either factor space has infinite dimension. We
show here that non-local states -- i.e., states whose correlations cannot be
reproduced by any local hidden variable model -- are also dense. Our
constructions distinguish between the cases where both factor spaces are
infinite-dimensional, where we show that states violating the CHSH inequality
are dense, and the case where only one factor space is infinite-dimensional,
where we identify open neighborhoods of nonseparable states that do not violate
the CHSH inequality but show that states with a subtler form of non-locality
(often called "hidden" non-locality) remain dense.Comment: 8 pages, RevTe
Connes' embedding problem and Tsirelson's problem
We show that Tsirelson's problem concerning the set of quantum correlations
and Connes' embedding problem on finite approximations in von Neumann algebras
(known to be equivalent to Kirchberg's QWEP conjecture) are essentially
equivalent. Specifically, Tsirelson's problem asks whether the set of bipartite
quantum correlations generated between tensor product separated systems is the
same as the set of correlations between commuting C*-algebras. Connes'
embedding problem asks whether any separable II factor is a subfactor of
the ultrapower of the hyperfinite II factor. We show that an affirmative
answer to Connes' question implies a positive answer to Tsirelson's.
Conversely, a positve answer to a matrix valued version of Tsirelson's problem
implies a positive one to Connes' problem
Generic Bell correlation between arbitrary local algebras in quantum field theory
We prove that for any two commuting von Neumann algebras of infinite type,
the open set of Bell correlated states for the two algebras is norm dense. We
then apply this result to algebraic quantum field theory -- where all local
algebras are of infinite type -- in order to show that for any two spacelike
separated regions, there is an open dense set of field states that dictate Bell
correlations between the regions. We also show that any vector state cyclic for
one of a pair of commuting nonabelian von Neumann algebras is entangled (i.e.,
nonseparable) across the algebras -- from which it follows that every field
state with bounded energy is entangled across any two spacelike separated
regions.Comment: Third version; correction in the proof of Proposition
Qualitative Environmental Health Research: An Analysis of the Literature, 1991-2008
BACKGROUND. Recent articles have advocated for the use of qualitative methods in environmental health research. Qualitative research uses nonnumeric data to understand people's opinions, motives, understanding, and beliefs about events or phenomena. OBJECTIVE. In this analysis of the literature, I report the use of qualitative methods and data in the study of the relationship between environmental exposures and human health. DATA SOURCES. A primary search on ISI Web of Knowledge/Web of Science for peer-reviewed journal articles dated from 1991 through 2008 included the following three terms: qualitative, environ*, and health. Inclusion and exclusion criteria are described. DATA EXTRACTION. Searches resulted in 3,155 records. Data were extracted and findings of articles analyzed to determine where and by whom qualitative environmental health research is conducted and published, the types of methods and analyses used in qualitative studies of environmental health, and the types of information qualitative data contribute to environmental health. DATA SYNTHESIS. Ninety-one articles met inclusion criteria. These articles were published in 58 different journals, with a maximum of eight for a single journal. The results highlight a diversity of disciplines and techniques among researchers who used qualitative methods to study environmental health, with most studies relying on one-on-one interviews. Details of the analyses were absent from a large number of studies. Nearly all of the studies identified increased scientific understanding of lay perceptions of environmental health exposures. DISCUSSION AND CONCLUSIONS. Qualitative data are published in traditionally quantitative environmental health studies to a limited extent. However, this analysis demonstrates the potential of qualitative data to improve understanding of complex exposure pathways, including the influence of social factors on environmental health, and health outcomes.National Institute of Environmental Health Sciences (R25 ES012084, P42ES007381
On the nature of continuous physical quantities in classical and quantum mechanics
Within the traditional Hilbert space formalism of quantum mechanics, it is
not possible to describe a particle as possessing, simultaneously, a sharp
position value and a sharp momentum value. Is it possible, though, to describe
a particle as possessing just a sharp position value (or just a sharp momentum
value)? Some, such as Teller (Journal of Philosophy, 1979), have thought that
the answer to this question is No -- that the status of individual continuous
quantities is very different in quantum mechanics than in classical mechanics.
On the contrary, I shall show that the same subtle issues arise with respect to
continuous quantities in classical and quantum mechanics; and that it is, after
all, possible to describe a particle as possessing a sharp position value
without altering the standard formalism of quantum mechanics.Comment: 26 pages, LaTe
Use of Ecological Sites in Managing Wildlife and Livestock: An Example with Prairie Dogs
On the Ground The perception of prairie dogs among Native Americans living on the Standing Rock Sioux Reservation is mixed. Some Native Americans focus on the loss of forage productivity, whereas others are interested in the cultural and ecological aspects of prairie dogs. The use of ecological sites may provide a mechanism for developing a management framework that would consider both livestock and prairie dogs. The three ecological sites we surveyed had large differences in off-colony standing crop, but in 2 of the 3 years we surveyed, there were no differences between standing crop on-colony. This suggests that management of prairie dogs on rangelands should focus on limiting prairie dogs on more productive ecological sites with less productive sites receiving less emphasis
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