Can conduction induce convection? The non-linear saturation of buoyancy instabilities in dilute plasmas

We study the effects of anisotropic thermal conduction on low-collisionality, astrophysical plasmas using two and three-dimensional magnetohydrodynamic simulations. For weak magnetic fields, dilute plasmas are buoyantly unstable for either sign of the temperature gradient: the heat-flux-driven buoyancy instability (HBI) operates when the temperature increases with radius while the magnetothermal instability (MTI) operates in the opposite limit. In contrast to previous results, we show that, in the presence of a sustained temperature gradient, the MTI drives strong turbulence and operates as an efficient magnetic dynamo (akin to standard, adiabatic convection). Together, the turbulent and magnetic energies contribute up to ~10% of the pressure support in the plasma. In addition, the MTI drives a large convective heat flux, ~1.5% of rho c_s^3. These findings are robust even in the presence of an external source of strong turbulence. Our results on the nonlinear saturation of the HBI are consistent with previous studies but we explain physically why the HBI saturates quiescently by re-orienting the magnetic field (suppressing the conductive heat flux through the plasma), while the MTI saturates by generating sustained turbulence. We also systematically study how an external source of turbulence affects the saturation of the HBI: such turbulence can disrupt the HBI only on scales where the shearing rate of the turbulence is faster than the growth rate of the HBI. In particular, our results provide a simple mapping between the level of turbulence in a plasma and the effective isotropic thermal conductivity. We discuss the astrophysical implications of these findings, with a particular focus on the intracluster medium of galaxy clusters.Comment: 18 pages, 14 figures. Submitted to MNRA

Collaboration Between Japanese and East African Universities: Creating Conversations to Promote Research and Understanding Among Faculty Members

Collaboration between and across universities on a personal rather than an institutional level is an effective way of sharing and learning from each other. All departments can gain from this type of collaborative effort between colleagues of different and even competing institutions. New or inexperienced university lecturers often struggle with the demands of university instruction and research. An exchange of ideas and points of view between instructors of varied levels of experience, or from different disciplines and institutions leads to deep professional growth and creates opportunities for career advancement. This paper will present a brief overview of the literature regarding practice and theory of academic collaboration, examine the benefits of inter- and intra-institutional collaboration, analyze one case study of collaboration between faculty members at three Japanese universities, and present a list of suggestions for implementation of academic collaboration in the East African context

Book Review: Frank Murphy: The Washington Years. by Sidney Fine.

Book review: Frank Murphy: The Washington Years. By Sidney Fine. Ann Arbor: University of Michigan Press. 1984. Pp. ix, 784. Reviewed by: Michael E. Parrish

Book Review: Zechariah Chafee, Jr.: Defender of Liberty and Law. by Donald L. Smith.

Book review: Zechariah Chafee, Jr.: Defender of Liberty and Law. By Donald L. Smith. Cambridge, Ma.: Harvard University Press. 1986. Pp. x, 355. Reviewed by: Michael E. Parrish

Domestic Life in Dutch New Amsterdam A Social Studies Curriculum for Third and Fourth Grade Children

This thesis presents a social studies curriculum for third and fourth grade students on the domestic life of New Amsterdam. Beginning with the geography of the region, the study focuses on the role that the environment has on meeting basic human needs of shelter, food and clothing. Based on a framework of objectives and ideas, the study is divided into three major units: shelter, food and clothing. Meeting each basic need required of New Amsterdam residents a vast amount of time and dedication. As children experience this curriculum, they can begin to understand the effort and many layered processes the initial Dutch settlers had to complete on a daily basis. Throughout the study students will extend and deepen their understandings by comparing the life in New Amsterdam to contemporary life in New York City. This study has been compiled from multiple resources that include journals, nonfiction texts, historical fiction, cookbooks, online resources, and maps. The curriculum is designed to offer children an opportunity to experience the daily life of New Amsterdam through sensory experiences, readings, videos, field trips and expressive writing

A Meta-Analysis of Questionaire Response Rates in Military Samples

The purpose of this research was to examine if factors related to questionnaire response rate in the general public also affect response rate in military-only samples. Very little research pertaining to this specific group was located during the literature review. Four response rate factors taken from studies conducted in the general public were selected for this research topic: questionnaire length, questionnaire delivery mode (postal, e-mail, web-based, direct administration, and mixed mode), use of advance notices, and use of follow-up reminders. Data were gathered for a meta-analysis of 73 previously published studies which utilized a survey or questionnaire to collect data from a military-only sample. After the data were analyzed, only two response rate factors produced significant results for this study: survey length and survey delivery mode. Results were discussed, and recommended research areas and conclusions are given

Book Review: Brandeis. by Lewis J. Paper.

Book review: Brandeis. By Lewis J. Paper. Englewood Cliffs: Prentice Hall, Inc. 1983. Pp. 442. Reviewed by Michael E Parrish

The Yellowhammer War: The Civil War and Reconstruction in Alabama

New Scholarship on the Civil War and Reconstruction in Alabama This volume features fourteen excellent essays, replete with full endnotes, by talented scholars who together present a sharp and challenging picture of Alabama during the Civil War era. The product of impressive organizationa...