Theory of the Lightly Doped Mott Insulator

A theory for the Hubbard model appropriate in the limit of large U/t, small doping away from half-filling and short-ranged antiferromagnetic spin correlations is presented. Despite the absence of any broken symmetry the Fermi surface takes the form of elliptical hole pockets centered near (pi/2,pi/2) with a volume proportional to the hole concentration. Short range antiferromagnetic correlations render the nearest neighbor hopping almost ineffective so that only second or third nearest neighbor hopping contributes appreciably to the dispersion relation.Comment: 9 pages, 3 figure

Analysis of the Discourse Between a Tutor and a Second Language Learner: A Joint Decoding Task

Tutors have a unique opportunity to help English-as-a Second Language (ESL) students develp their communicative competence. Mary Ann Christison and Karl Krahnke found that ESL students rated social contact as the largest contributor to language development outside the classroom, but also the area most lacking.* Tutoring may be one way to provide social contact, while at the same time providing help with language, cultural, and academic difficulties ESL students may be facing. Potential ESL tutors may be uncertain, however, about the role they are supposed to play in the tutoring situation. *Christison, Mary Ann, and Karl J. Krahnke. Student Perceptions of Academic Language Study. TESOL Quarterly 20.1 (1986):61-79

The Teacher As Revolutionary: Paolo Freire

Teaching can be a very lonely occupation. On one hand, we wonder what effect, if any, we are having on the great array of problems which life presents to our students. On the other, they may seem disinterested or rebellious. Our own lives may not accomplish the goals we devised when we were inspired, and we look about for ways to make them more meaningful. The story of a teacher whose students, illiterate peasants in the backwaters of Brazil, transformed their own lives, and his, has a certain appeal. Does this man, Paolo Freire, have anything to say to us, here in the United States, especially when it is our ethnocentric impression that most of his students would gladly immigrate here if given the chance? Freire may not be able to give us the solution to our malaise, but he may be able to help us find the questions we need to begin asking ourselves

First Experiences Integrating PC Distributed I/O Into Argonne's ATLAS Control System

First Experiences Integrating PC Distributed I/O Into Argonne's ATLAS Control System The roots of ATLAS (Argonne Tandem-Linac Accelerator System) date back to the early 1960s. Located at the Argonne National Laboratory, the accelerator has been designated a National User Facility, which focuses primarily on heavy-ion nuclear physics. Like the accelerator it services, the control system has been in a constant state of evolution. The present real-time portion of the control system is based on the commercial product Vsystem [1]. While Vsystem has always been capable of distributed I/O processing, the latest offering of this product provides for the use of relatively inexpensive PC hardware and software. This paper reviews the status of the ATLAS control system, and describes first experiences with PC distributed I/O.Comment: ICALEPCS 2001 Conference, PSN WEAP027, 3 pages, 1 figur

DOCUMENTING CHANGE AT UPPER HAMBURG BEND: NEBRASKA\u27S FIRST SIDE-CHANNEL RESTORATION

In 1996 a side channel was excavated on 629 hectares of former agricultural land at Upper Hamburg Bend on the Missouri River in Otoe County, NE. This was the first side channel constructed on the Missouri River in an attempt to restore lost aquatic habitat. The initial design was for an approximately 4,200 m long side channel to be constructed with a 3 m bottom width. Development ofthe site was to be dependent on flows diverted from the main channel of the river with a final projected top width of 61 m. The side channel was completed in the spring, and shortly thereafter the site was subjected to a series of flood events. The side channel has been subjected to periods of both high and low water since opening. We documented physical changes at the site with the aid of aerial photography, acoustic Doppler current profiler (ADCP) surveys, and topographic surveys. By 2010 the side channel was 4,342 m long with a mean top width of89.5 m. Channel development has occurred during periods of high and low water. ADCP surveys established that mean depths and velocities have increased since 2001. An increase in the amount of discharge through the side channel since 2001 has resulted in the loss of some of the shallower and lower velocity habitats. Modifications to the site may be necessary to reverse this loss of shallow, slow water habitat that the side channel was designed to provide. Although new off-channel aquatic habitat has been created, channel development has been impacted by the presence of rock control structures throughout the site. Reducing the number of control structures to the minimum necessary to prohibit the side channel from impacting adjacent properties may allow the continued restoration of lost alluvial processes through the ongoing process of bend development and migration

DOCUMENTING CHANGE AT UPPER HAMBURG BEND: NEBRASKA\u27S FIRST SIDE-CHANNEL RESTORATION

In 1996 a side channel was excavated on 629 hectares of former agricultural land at Upper Hamburg Bend on the Missouri River in Otoe County, NE. This was the first side channel constructed on the Missouri River in an attempt to restore lost aquatic habitat. The initial design was for an approximately 4,200 m long side channel to be constructed with a 3 m bottom width. Development ofthe site was to be dependent on flows diverted from the main channel of the river with a final projected top width of 61 m. The side channel was completed in the spring, and shortly thereafter the site was subjected to a series of flood events. The side channel has been subjected to periods of both high and low water since opening. We documented physical changes at the site with the aid of aerial photography, acoustic Doppler current profiler (ADCP) surveys, and topographic surveys. By 2010 the side channel was 4,342 m long with a mean top width of89.5 m. Channel development has occurred during periods of high and low water. ADCP surveys established that mean depths and velocities have increased since 2001. An increase in the amount of discharge through the side channel since 2001 has resulted in the loss of some of the shallower and lower velocity habitats. Modifications to the site may be necessary to reverse this loss of shallow, slow water habitat that the side channel was designed to provide. Although new off-channel aquatic habitat has been created, channel development has been impacted by the presence of rock control structures throughout the site. Reducing the number of control structures to the minimum necessary to prohibit the side channel from impacting adjacent properties may allow the continued restoration of lost alluvial processes through the ongoing process of bend development and migration

Stylistic Fingerprints, POS-tags and Inflected Languages: A Case Study in Polish

In stylometric investigations, frequencies of the most frequent words (MFWs) and character n-grams outperform other style-markers, even if their performance varies significantly across languages. In inflected languages, word endings play a prominent role, and hence different word forms cannot be recognized using generic text tokenization. Countless inflected word forms make frequencies sparse, making most statistical procedures complicated. Presumably, applying one of the NLP techniques, such as lemmatization and/or parsing, might increase the performance of classification. The aim of this paper is to examine the usefulness of grammatical features (as assessed via POS-tag n-grams) and lemmatized forms in recognizing authorial profiles, in order to address the underlying issue of the degree of freedom of choice within lexis and grammar. Using a corpus of Polish novels, we performed a series of supervised authorship attribution benchmarks, in order to compare the classification accuracy for different types of lexical and syntactic style-markers. Even if the performance of POS-tags as well as lemmatized forms was notoriously worse than that of lexical markers, the difference was not substantial and never exceeded ca. 15%

Temperature dependent band structure of the Kondo insulator

We present a Qantum Monte Carlo (QMC) study of the temperature dependent dynamics of the Kondo insulator. Working at the so-called symmetrical point allows to perform minus-sign free QMC simulations and thus reach temperatures of less than 1% of the conduction electron bandwidth. Study of the temperature dependence of the single particle Green's function and dynamical spin correlation function shows a surprisingly intricate low temperature band structure and gives evidence for two characteristic temperatures, which we identify with the Kondo and coherence temperature, respectively. In particular, the data show a temperature induced metal-insulator transition at the coherence temperature.Comment: RevTex-file, 4 PRB pages with 4 eps figures. Hardcopies of figures (or the entire manuscript) can be obtained by e-mail request to: [email protected]

Modeling the dynamics of language change: logistic regression, Piotrowski's law, and a handful of examples in Polish

The study discusses modeling diachronic processes by logistic regression. The phenomenon of nonlinear changes in language was first observed by Raimund Piotrowski (hence labelled as Piotrowski's law), even if actual linguistic evidence usually speaks against using the notion of a "law" in this context. In our study, we apply logistic regression models to 9 changes which occurred between 15th and 18th century in the Polish language. The attested course of the majority of these changes closely follow the expected values, which proves that the language change might indeed resemble a nonlinear phase change scenario. We also extend the original Piotrowski's approach by proposing polynomial logistic regression for these cases which can hardly be described by its standard version. Also, we propose to consider individual language change cases jointly, in order to inspect their possible collinearity or, more likely, their different dynamics in the function of time. Last but not least, we evaluate our results by testing the influence of the subcorpus size on the model's goodness-of-fit

Propiedades Organolépticas y Volátiles del Torrontés Riojano Espumante

Torrontés Riojano is a signature Argentina’s white-wine grape varietal. The moderate acidity and floral aromas of this varietal, reminiscent of Muscat and Gewürtztraminer varietals, make Torrontés Riojano a valuable resource to prepare sparkling wine. We studied in this work the organoleptic characteristics of Torrontés Riojano sparkling wine prepared using bottle second fermentation and industrial yeast strain EC1118. The resulting sparkling wine, following an aging period of twelve-months, was subjected to comprehensive chemical, solid phase extraction and gas  hromatography–mass spectrometry analyses for identification and quantification of relevant oenological metabolites. Volatile compoundswere quantified after adsorption and separate elution with dichloromethane from an Isolute ENV+ cartridge1. Compounds were identified by comparison of their linear retention indices (LRI) in the mass spectra with those from pure standards or reported in the literature2. In addition, a panel of fourteen expert assessors defined the sensory aroma properties on two randomly selected sparkling wines bottles. Panelists rated secondary and tertiary tier terms using a 10-point intensity scale3. Our results show that strain EC1118 was capable of completing secondary fermentation, resulting in non-defective sparkling wine that preserves the rich aromatic profiles recognized in Torrontés Riojanowines4. This work represents the first analysis of the chemical and sensory characteristics of the Torrontés Riojano sparkling wine