The Drell-Hearn Sum Rule at Order Alpha**3

The Drell-Hearn-Gerasimov-Iddings (DHGI) sum rule for electrons is evaluated at order $\alpha^3$ and shown to agree with the Schwinger contribution to the anomalous magnetic moment.Comment: 3 pages, 1 figur

Mobility of slow electrons in a polar crystal

We have obtained an approximate expression for the impedance function at all frequencies, temperatures, and coupling strengths of an electron coupled to a polar lattice (a system commonly called a polaron). The starting point for the calculation is the quantum mechanical expression for the expected current. The phonon coordinates are eliminated from this expression by well-known field-theory techniques. The resulting exact "influence functional" is then approximated by a corresponding quadratic "influence functional" which, it is hoped, imitates the real polaron. Correction terms are computed to account for the difference between the approximate impedance and the exact polaron impedance in a manner closely analogous to Feynman's treatment of the polaron self-energy. In fact, the analytic evaluation of the expression for the impedance obtained here is carried out using the approximate "influence functional" that was successfully employed in minimizing the binding (and free) energy of the polaron in earlier calculations. However, the accuracy obtained using this approximation, for the impedance calculation, is less satisfactory and its limitations are discussed. Nevertheless, beginning at intermediate coupling strengths, the approximate impedance produces a level structure of increasing complexity and narrowing resonances as the coupling strengthens. This suggests that further refinements may be fruitful. Methods for finding a better quadratic influence functional for use in our impedance expression as well as ways of improving the expression further are suggested. A comparison of our results with those of the Boltzmann equation points up interesting differences which arise from reversing the order of taking limits of zero frequency and coupling

Proton structure corrections to electronic and muonic hydrogen hyperfine splitting

We present a precise determination of the polarizability and other proton structure dependent contributions to the hydrogen hyperfine splitting, based heavily on the most recent published data on proton spin dependent structure functions from the EG1 experiment at the Jefferson Laboratory. As a result, the total calculated hyperfine splitting now has a standard deviation slightly under 1 part-per-million, and is about 1 standard deviation away from the measured value. We also present results for muonic hydrogen hyperfine splitting, taking care to ensure the compatibility of the recoil and polarizability terms.Comment: 9 pages, 1 figur

On breaking ground: Second language literacy and language learning through sociocultural practices

This study was concerned with (a) how second language children actually learn as a result of their social interactions; (b) the learning trajectory of second language students from apprentice to full participation in communities of practice; and (c) how this learning influences, and is reciprocally influenced by, the social, cultural, and historical context as learners become members of community practice. These questions were investigated under the lens of sociocultural theory, which emphasizes leaning in relationship with others and with materials over time within the social context; This was a qualitative study involving genetic methodology (Vygostky, 1981) which aims to understand, rather than describe, mental processes through the disclosure of their emergence and subsequent growth. Participants in this study were second language students included in two mainstream classroom of a year-round school in an urban district in the Southwest. Methods of data collection included the videotaping of children in authentic (non-contrived) interactions; interviews with participating students, teachers, and parents of participating students; field notes of classroom observations; and anecdotal records of participating students. Genetic analysis of these data afforded the possibility of focusing on the social context in which learning takes place; The results of this study point to a departure from conceptualizations of second language learning as a skill, and instead views L2 learning as a process of reconceptualization of the self. It was also learned in this study that cultural, social, historical, and institutional elements of the learning context both contribute and restrict L2 legitimate participation in communities of practice. These elements are contributing when students are free to utilize their sociocultural and historical repertoire as mediational tools to make sense of the educational environment (e.g., through the use of hybrid language practices, home discourse patterns, practices that allow for self-expression, and authentic forms of assessment). They are restrictive when institutional aspects are privileged within the classroom context (e.g., by the emphasis on procedural elements, use of official discourse, hegemony of English, monological practices, and legitimizing forms of assessment). It was also suggested in this study that sociocultural, historical, and institutional aspects of the classroom contexts might have been largely ignored by traditional research, and thus this fact has become reflected in praxis

A Functional Analysis of English Humanities and Biochemistry Writing with Respect to Teaching University Composition

This thesis examines how writing differs in both English departments and Biochemistry departments in realization at the grammatical, that is, the lexico-grammatical level; and thus, how the differing writing modes are not merely realizations of differences at the lexical level, but the grammar of the texts is affected by the different world perspectives reflected by each discipline. By analyzing the lexico-grammatical realizations in texts produced by professionals in both the English and Biochemistry disciplines, through the analysis of basic writing handbooks which are required reading for many introductory writing students, and through analysis of a survey given to full-time university composition professors, this study examines not only how the two disciplines write differently, but more importantly, the implications of current strategies of teaching basic writing composition for academic purposes. All of these implications are examined utilizing the theory of Systemic Functional Linguistics. The thesis argues that lexico- grammar reflects and is reflected by the world perspective of each discipline; thus teaching traditional school grammar (i.e., subject verb agreement, punctuation, spelling, etc.) and traditional English Humanities type lexico-grammatical realizations in the basic writing class falls outside the scope of teaching functional writing for all academic purposes. Therefore, the traditional approach in teaching composition, and even recent trends toward teaching writing as a process, still falls short of the implications which teaching alternative lexico-grammatical realization patterns can have when discourse-level phenomena are discussed within and without the English Humanities discipline rather than just clause-level phenomena. Therefore, as composition courses continue to teach toward realizations of English Humanities’ lexico- grammar, students who desire to work outside this discipline may not be as prepared as instructors would like, contrary to what some professors within English departments have commonly believed

Proton polarizability contribution to the hyperfine splitting in muonic hydrogen

The contribution of the proton polarizability to the ground state hyperfine splitting in muonic hydrogen is evaluated on the basis of modern experimental and theoretical results on the proton polarized structure functions. The value of this correction is equal to 4.6(8)\cdot 10^{-4} times the Fermi splitting E_F.Comment: 10 pages (revtex), 5 figure

Revisiting Menstrual Bleeding Patterns in Adolescents Using Etonogestrel (ENG) Implant

Etonogestrel (ENG) implant is an effective method of contraception. The implant is designed to provide contraceptive efficacy for three years with a relatively quick return of fertility upon its removal. Dysfunctional uterine bleeding (DUB) is a common side effect of long acting progestins and is often the reason patients state for removal or discontinuation. A retrospective chart analysis was completed on 292 patients who chose to be on the ENG implant. Age of patients ranged from 10-29 years of age with the average age at implant being 17 years +/- 3 years. Patients retained implant for 1-68 months with the average use being 21.0 months +/- 15.5 months. Over the 69 month period, 158 patients had the complaint of DUB (54.1%) and 46 patients with DUB had their implants removed because DUB was unresolved upon treatment and/or follow up (15.6%). Therefore, is it import for clinicians to be aware of the likelihood of DUB with implant usage and for them to be able to provide appropriate pre and post insertion counseling and treatment to all of their patients