9,820 research outputs found
Recent progress on truncated Toeplitz operators
This paper is a survey on the emerging theory of truncated Toeplitz
operators. We begin with a brief introduction to the subject and then highlight
the many recent developments in the field since Sarason's seminal paper in
2007.Comment: 46 page
Real complex functions
We survey a few classes of analytic functions on the disk that have real
boundary values almost everywhere on the unit circle. We explore some of their
properties, various decompositions, and some connections these functions make
to operator theory.Comment: 44 page
Science education on the U.S./Mexico border: Field-based studies for future teachers in bilingual/binational schools
The University of Texas at El Pasoâs field-based program of studies for future teachers provides opportunities for powerful learning through a dialectical union of reflection and action. Methods courses in academic disciplines are linked with seminars and coursework on community partnerships, dual language education and culturally responsive education. This article illustrates the processes of planning, implementation and evaluation of this approach, highlighting the impacts of forging connections among schools, communities and university personnel to improve education on the U.S./Mexico border and in communities with culturally/linguistically diverse student populations. Parents, students and future teachers interact in bilingual workshops that center on pupil achievement and conceptually correct science education. Preliminary outcomes indicate that two-way dual language (TWDL) bilingual programs (i.e., validating native language literacy along with English language acquisition) with a strong parental engagement component provide a strong framework for teaching/learning that can help improve educational outcomes for ELL/immigrant children and deepen future teachersâ skills and knowledge. Focusing on academic enrichment for all students, these field-based experiences enable future teachers to learn strategies that integrate studentsâ and familiesâ linguistic and cultural experiences as a resource for learning. The co-authors highlight qualitative data findings from the Science in Our Homes â Ciencia en Nuestras Casas field-based project in a multilingual, multicultural K-8 school on the U.S./Mexico border, providing insights for educators in diverse communities whose efforts focus on closing the achievement gap for English language learners and/or immigrant students
Gravitational Binding, Virialization and the Peculiar Velocity Distribution of the Galaxies
We examine the peculiar velocity distribution function of galaxies in
cosmological many-body gravitational clustering. Our statistical mechanical
approach derives a previous basic assumption and generalizes earlier results to
galaxies with haloes. Comparison with the observed peculiar velocity
distributions indicates that individual massive galaxies are usually surrounded
by their own haloes, rather than being embedded in common haloes. We then
derive the density of energy states, giving the probability that a randomly
chosen configuration of N galaxies in space is bound and virialized.
Gravitational clustering is very efficient. The results agree well with the
observed probabilities for finding nearby groups containing N galaxies. A
consequence is that our local relatively low mass group is quite typical, and
the observed small departures from the local Hubble flow beyond our group are
highly probable.Comment: Paper in aastex 5.0 format and 9 figures. Replace a new version with
figures and typos correcte
Agricultural Price Distortion and Stabilization: Stylized facts and Hypothesis Tests
This paper describes agricultural policy choices and tests some predictions of political economy theories. It begins with three broad stylized facts: governments tend to tax agriculture in poorer countries, and subsidize it in richer ones, tax both imports and exports more than nontradables, and tax more and subsidize less where there is more land per capita. We test a variety of political-economy explanations, finding results consistent with hypothesized effects of rural and urban constituentsâ rational ignorance about small per-person effects, governance institutionsâ control of rent-seeking by political leaders, governmentsâ revenue motive for taxation, and the role of time consistency in policy-making. We also find that larger groups obtain more favorable policies, suggesting that positive group size effects outweigh any negative influence from more free-ridership, and that demographically driven entry of new farmers is associated with less favorable farm policies, suggesting the arrival of new farmers erodes policy rents and discourages political activity by incumbents. Another new result is that governments achieve very little price stabilization relative to our benchmark estimates of undistorted prices, and governments in the poorest countries actually destabilize domestic prices.Distorted incentives, agricultural and trade policy reforms, national agricultural development, Agricultural price distortions, political economy, Agricultural and Food Policy, International Relations/Trade, F13, F14, Q17, Q18, D72, D78, F11, H23,
-algebras generated by truncated Toeplitz operators
We obtain an analogue of Coburn's description of the Toeplitz algebra in the
setting of truncated Toeplitz operators. As a byproduct, we provide several
examples of complex symmetric operators which are not unitarily equivalent to
truncated Toeplitz operators having continuous symbols.Comment: 12 page
Unitary equivalence to a truncated Toeplitz operator: analytic symbols
Unlike Toeplitz operators on , truncated Toeplitz operators do not have
a natural matricial characterization. Consequently, these operators are
difficult to study numerically. In this note we provide criteria for a matrix
with distinct eigenvalues to be unitarily equivalent to a truncated Toeplitz
operator having an analytic symbol. This test is constructive and we illustrate
it with several examples. As a byproduct, we also prove that every complex
symmetric operator on a Hilbert space of dimension is unitarily
equivalent to a direct sum of truncated Toeplitz operators.Comment: 15 page
Spatial isomorphisms of algebras of truncated Toeplitz operators
We examine when two maximal abelian algebras in the truncated Toeplitz
operators are spatially isomorphic. This builds upon recent work of N. Sedlock,
who obtained a complete description of the maximal algebras of truncated
Toeplitz operators.Comment: 24 page
- âŠ