Nutrition and Arthritis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72590/1/j.1753-4887.1949.tb02151.x.pd

Operator-Valued Frames for the Heisenberg Group

A classical result of Duffin and Schaeffer gives conditions under which a discrete collection of characters on $\mathbb{R}$, restricted to $E = (-1/2, 1/2)$, forms a Hilbert-space frame for $L^2(E)$. For the case of characters with period one, this is just the Poisson Summation Formula. Duffin and Schaeffer show that perturbations preserve the frame condition in this case. This paper gives analogous results for the real Heisenberg group $H_n$, where frames are replaced by operator-valued frames. The Selberg Trace Formula is used to show that perturbations of the orthogonal case continue to behave as operator-valued frames. This technique enables the construction of decompositions of elements of $L^2(E)$ for suitable subsets $E$ of $H_n$ in terms of representations of $H_n$

Analytic Scattering and Refraction Models for Exoplanet Transit Spectra

Observations of exoplanet transit spectra are essential to understanding the physics and chemistry of distant worlds. The effects of opacity sources and many physical processes combine to set the shape of a transit spectrum. Two such key processes - refraction and cloud and/or haze forward scattering - have seen substantial recent study. However, models of these processes are typically complex, which prevents their incorporation into observational analyses and standard transit spectrum tools. In this work, we develop analytic expressions that allow for the efficient parameterization of forward scattering and refraction effects in transit spectra. We derive an effective slant optical depth that includes a correction for forward scattered light, and present an analytic form of this correction. We validate our correction against a full-physics transit spectrum model that includes scattering, and we explore the extent to which the omission of forward scattering effects may bias models. Also, we verify a common analytic expression for the location of a refractive boundary, which we express in terms of the maximum pressure probed in a transit spectrum. This expression is designed to be easily incorporated into existing tools, and we discuss how the detection of a refractive boundary could help indicate the background atmospheric composition by constraining the bulk refractivity of the atmosphere. Finally, we show that opacity from Rayleigh scattering and collision induced absorption will outweigh the effects of refraction for Jupiter-like atmospheres whose equilibrium temperatures are above 400-500 K.Comment: ApJ accepted; submitted Feb. 7, 201

H-alpha Activity of Old M Dwarfs: Stellar Cycles and Mean Activity Levels For 93 Low-Mass Stars in the Solar Neighborhood

Through the McDonald Observatory M Dwarf Planet Search, we have acquired nearly 3,000 high-resolution spectra of 93 late-type (K5-M5) stars over more than a decade using HET/HRS. This sample provides a unique opportunity to investigate the occurrence of long-term stellar activity cycles for low-mass stars. In this paper, we examine the stellar activity of our targets as reflected in the H-alpha feature. We have identified periodic signals for 6 stars, with periods ranging from days to more than 10 years, and find long-term trends for 7 others. Stellar cycles with P > 1 year are present for at least 5% of our targets. Additionally, we present an analysis of the time-averaged activity levels of our sample, and search for correlations with other stellar properties. In particular, we find that more massive, earlier type (M0-M2) stars tend to be more active than later type dwarfs. Furthermore, high-metallicity stars tend to be more active at a given stellar mass. We also evaluate H-alpha variability as a tracer of activity-induced radial velocity (RV) variation. For the M dwarf GJ 1170, H-alpha variation reveals stellar activity patterns matching those seen in the RVs, mimicking the signal of a giant planet, and we find evidence that the previously identified stellar activity cycle of GJ 581 may be responsible for the recently retracted planet f (Vogt et al. 2012) in that system. In general, though, we find that H-alpha is not frequently correlated with RV at the precision (typically 6-7 m/s) of our measurements.Comment: Submitted to ApJ. Reflects comments from a positive refere

Implementing RTI in Two Rural Elementary Schools: Encouraging Beginnings and Challenges for the Future

Response to Intervention (RTI) models are currently being implemented in many school districts nationwide. However, at a time when interest in RTI is high, the extent to which it is being implemented effectively in rural schools is largely unknown. Teachers and administrators in two rural elementary schools in the Southeastern United States who were part of a state-wide RTI pilot project participated in this study. Interviews were conducted along with field observations of classroom instruction and team problem-solving meetings. Using a multi-step process for data analysis, various implementation themes emerged related to tiered instruction, data-based decision making, support for model implementation, and collaboration. Findings in these areas support issues raised in the literature regarding factors in rural schools that may impede or enhance fidelity of model implementation. Implications for practice and future research are discussed

High-level synthesis for medical image processing on Systems on Chip : a case study

Adaptive radiotherapy is a technique intended to increase the accuracy of radiotherapy. Currently, it is not clinically feasible due to the time required to process the images of patient anatomy. Hardware acceleration of image processing algorithms may allow them to be carried out in a clinically acceptable timeframe. This paper presents the experiences encountered using high-level synthesis tools to design an accelerated segmentation algorithm for computed tomography images targeted for implementation on a System on Chip. Hardware coprocessors and their interfaces for optimal threshold generation and 3D mean filter algorithms were synthesised from C++ functions. Hardware acceleration significantly outperformed the software only implementation. The high-level synthesis tools allowed the rapid exploration of different design options. However, hardware design knowledge was still necessary in order to interpret the results effectively

Using a White-Collar Profession in accounting courses: Approaches to addressing diversity

Accounting educators no doubt agree that diversity is an important and much neglected part of accounting education. They further recognize that it is difficult to incorporate this important topic into the accounting curriculum. This paper describes the efforts of various professors to expose business and accounting students to the evolution of diversity issues related to the accounting profession by using the book A White-Collar Profession [Hammond, 2002]. A White-Collar Profession: African-American CPAs Since 1921 is a seminal work which presents a history of the profession as it relates to African-American CPAs and documents the individual struggles of many of the first one hundred blacks to become certified. This paper describes efforts of faculty at four different colleges to utilize this book in their teaching of accounting. Instructors found that students not only developed an enhanced awareness about the history of the accounting profession, but that other educational objectives were advanced, such as improved communication and critical thinking skills, increased social awareness, and empathy for others. African-American students, in particular, embraced the people in the book as role models, while most every student saw the characters as heroic in a day when the accounting profession is badly in need of role models and heroes. This is encouraging given the profession\u27s concern with diversity and the attention and resources directed at increasing the number of minorities entering the profession