STUDY OF A DIRECT SAMPLING METHOD FOR THE INVERSE MEDIUM SCATTERING PROBLEM

Direct sampling methods are increasingly being used to solve the inverse medium scattering problem to estimate the shape of the scattering object. A simple direct method using one incident wave and multiple measurements was proposed by Ito, Jin and Zou. In this report, we performed some analytic and numerical studies of the direct sampling method. The method was found to be effective in general. However, there are a few exceptions exposed in the investigation. Analytic solutions in different situations were studied to verify the viability of the method while numerical tests were used to validate the effectiveness of the method.

"The need obliged us" : culture as capacity during the Hurricane Stan emergency response. A case study from Tectitan, Huehuetenango, Guatemala

A major deficiency in disaster management plans is the assumption that pre-disaster civil-society does not have the capacity to respond effectively during crises. Following from this assumption a dominant emergency management strategy is to replace weak civil-society organizations with specialized disaster organizations that are often either military or Para-military and seek to centralize decision-making. Many criticisms have been made of this approach, but few specifically addresses disasters in the developing world. Disasters in the developing world present unique problems not seen in the developed world because they often occur in the context of compromised governments, and marginalized populations. In this context it is often community members themselves who possess the greatest capacity to respond to disasters. This paper focuses on the capacity of community groups to respond to disaster in a small town in rural Guatemala. Key informant interviews and ethnographic observations are used to reconstruct the community response to the disaster instigated by Hurricane Stan (2005) in the municipality of Tectit��n in the Huehuetenango department. The interviews were analyzed using techniques adapted from grounded theory to construct a narrative of the events, and identify themes in the community���s disaster behavior. These themes are used to critique the emergency management plans advocated by the Guatemalan National Coordination for the Reduction of Disasters (CONRED). This paper argues that CONRED uncritically adopts emergency management strategies that do not account for the local realities in communities throughout Guatemala. The response in Tectit��n was characterized by the formation of new organizations, whose actions and leadership structure were derived from ���normal��� or routine life. It was found that pre-existing social networks were resilient and easily re-oriented meet the novel needs of a crisis. New or emergent groups that formed during the disaster utilized social capital accrued by routine collective behavior, and employed organizational strategies derived from ���normal��� community relations. Based on the effectiveness of this response CONRED could improve its emergency planning on the local-level by utilizing the pre-existing community organizations rather than insisting that new disaster-specific organizations be formed.

Attempting to improve standardized test results using Study Islands' web-based mastery program

State standardized testing has always been a tool to measure a school���s performance and to help evaluate school curriculum. However, with the school of choice legislation in 1992, the MEAP test became a measuring stick to grade schools by and a major tool in attracting school of choice students. Now, declining enrollment and a state budget struggling to stay out of the red have made school of choice students more important than ever before. MEAP scores have become the deciding factor in some cases. For the past five years, the Hancock Middle School staff has been working hard to improve their students��� MEAP scores in accordance with President Bush's ���No Child Left Behind��� legislation. In 2005, the school was awarded a grant that enabled staff to work for two years on writing and working towards school goals that were based on the improvement of MEAP scores in writing and math. As part of this effort, the school purchased an internet-based program geared at giving students practice on state content standards. This study examined the results of efforts by Hancock Middle School to help improve student scores in mathematics on the MEAP test through the use of an online program called ���Study Island.��� In the past, the program was used to remediate students, and as a review with an incentive at the end of the year for students completing a certain number of objectives. It had also been used as a review before upcoming MEAP testing in the fall. All of these methods may have helped a few students perform at an increased level on their standardized test, but the question remained of whether a sustained use of the program in a classroom setting would increase an understanding of concepts and performance on the MEAP for the masses. This study addressed this question. Student MEAP scores and Study Island data from experimental and comparison groups of students were compared to understand how a sustained use of Study Island in the classroom would impact student test scores on the MEAP. In addition, these data were analyzed to determine whether Study Island results provide a good indicator of students��� MEAP performance. The results of the study suggest that there were limited benefits related to sustained use of Study Island and gave some indications about the effectiveness of the mathematics curriculum at Hancock Middle School. These results and implications for instruction are discussed.

Electronic properties of zig-zag carbon nanotubes : a first-principles study

Carbon nanotube (CNT) is a one dimensional (1-D) nanostructured material, which has been the focal point of research over the past decade for intriguing applications ranging from nanoelectronics to chemical and biological sensors. Using a first-principles gradient corrected density functional approach, we present a comprehensive study of the geometry and energy band gap in zig-zag semi-conducting (n,0) carbon nanotubes (CNT) to resolve some of the conflicting findings. Our calculations confirm that the single wall (n,0) CNTs fall into two distinct classes depending upon n mod 3 equal to 1 (smaller band gaps) or 2 (larger gaps). The effect of longitudinal strain on the band gap further confirms the existence of two distinct classes: for n mod 3 = 1 or 2, changing Eg by ~ ��110 meV for 1% strain in each case. We also present our findings for the origin of metallicity in multiwall CNTs.

Development of a high performance parallel computing platform and its use in the study of nanostructures : clusters, sheets and tubes .

Small clusters of gallium oxide, technologically important high temperature ceramic, together with interaction of nucleic acid bases with graphene and small-diameter carbon nanotube are focus of first principles calculations in this work. A high performance parallel computing platform is also developed to perform these calculations at Michigan Tech. First principles calculations are based on density functional theory employing either local density or gradient-corrected approximation together with plane wave and gaussian basis sets. The bulk Ga2O3 is known to be a very good candidate for fabricating electronic devices that operate at high temperatures. To explore the properties of Ga2O3 at nonoscale, we have performed a systematic theoretical study on the small polyatomic gallium oxide clusters. The calculated results find that all lowest energy isomers of GamOn clusters are dominated by the Ga-O bonds over the metal-metal or the oxygen-oxygen bonds. Analysis of atomic charges suggest the clusters to be highly ionic similar to the case of bulk Ga2O3. In the study of sequential oxidation of these slusters starting from Ga2O, it is found that the most stable isomers display up to four different backbones of constituent atoms. Furthermore, the predicted configuration of the ground state of Ga2O is recently confirmed by the experimental result of Neumark's group. Guided by the results of calculations the study of gallium oxide clusters, performance related challenge of computational simulations, of producing high performance computers/platforms, has been addressed. Several engineering aspects were thoroughly studied during the design, development and implementation of the high performance parallel computing platform, rama, at Michigan Tech. In an attempt to stay true to the principles of Beowulf revolutioni, the rama cluster was extensively customized to make it easy to understand, and use - for administrators as well as end-users. Following the results of benchmark calculations and to keep up with the complexity of systems under study, rama has been expanded to a total of sixty four processors. Interest in the non-covalent intereaction of DNA with carbon nanotubes has steadily increased during past several years. This hybrid system, at the junction of the biological regime and the nanomaterials world, possesses features which make it very attractive for a wide range of applicatioins. Using the in-house computational power available, we have studied details of the interaction between nucleic acid bases with graphene sheet as well as high-curvature small-diameter carbon nanotube. The calculated trend in the binding energies strongly suggests that the polarizability of the base molecules determines the interaction strength of the nucleic acid bases with graphene. When comparing the results obtained here for physisorption on the small diameter nanotube considered with those from the study on graphene, it is observed that the interaction strength of nucleic acid bases is smaller for the tube. Thus, these results show that the effect of introducing curvature is to reduce the binding energy. The binding energies for the two extreme cases of negligible curvature (i.e. flat graphene sheet) and of very high curvature (i.e. small diameter nanotube) may be considered as upper and lower bounds. This finding represents an important step towards a better understanding of experimentally observed sequence-dependent interaction of DNA with Carbon nanotubes.

Teaching and aligning upper level mathematics classes to Michigan high school content expectations in an alternative education setting : approaches and issues

After teaching regular education secondary mathematics for seven years, I accepted a position in an alternative education high school. Over the next four years, the State of Michigan adopted new graduation requirements phasing in a mandate for all students to complete Geometry and Algebra 2 courses. Since many of my students were already struggling in Algebra 1, getting them through Geometry and Algebra 2 seemed like a daunting task. To better instruct my students, I wanted to know how other teachers in similar situations were addressing the new High School Content Expectations (HSCEs) in upper level mathematics. This study examines how thoroughly alternative education teachers in Michigan are addressing the HSCEs in their courses, what approaches they have found most effective, and what issues are preventing teachers and schools from successfully implementing the HSCEs. Twenty-six alternative high school educators completed an online survey that included a variety of questions regarding school characteristics, curriculum alignment, implementation approaches and issues. Follow-up phone interviews were conducted with four of these participants. The survey responses were used to categorize schools as successful, unsuccessful, and neutral schools in terms of meeting the HSCEs. Responses from schools in each category were compared to identify common approaches and issues among them and to identify significant differences between school groups. Data analysis showed that successful schools taught more of the HSCEs through a variety of instructional approaches, with an emphasis on varying the ways students learned the material. Individualized instruction was frequently mentioned by successful schools and was strikingly absent from unsuccessful school responses. The main obstacle to successful implementation of the HSCEs identified in the study was gaps in student knowledge. This caused pace of instruction to also be a significant issue. School representatives were fairly united against the belief that the Algebra 2 graduation requirement was appropriate for all alternative education students. Possible implications of these findings are discussed.

INCORPORATING STIMULATING QUICK-WRITE PROMPTS WITHIN A SECONDARY SCIENCE CLASSROOM: A CASE STUDY IN LESOTHO

The use of intriguing open-ended quick-write prompts within the Basotho science classroom could potentially provide a way for secondary teachers in Lesotho to have a time-efficient alternative to stimulate student thinking and increase critical thinking or application of scientific principles. Writing can be used as a powerful means to improve the achievement of students across many subject areas, including the sciences (Moore, 1993; Rivard, 1994; Rillero, Zambo, Cleland, and Ryan, 1996; Greenstein, 2013). This study focuses on the use of a non-traditional nor extensively studied writing method that could potentially support learning in science. A quasi-experimental research design, with a control and experimental group, was applied. The study was conducted at two schools, with one experimental classroom in one school and a second control group classroom in the second school for a period of 4 weeks. 51 Form B (US Grade 9 equivalent) students participated as the experimental group and 43 Form B students as the control group. In an effort to assess learning achievement, a 1 hour (35 mark) pre-test evaluation was made by and given to students by Basotho teachers at the beginning of this study to have an idea of student���s previous knowledge. Topics covered were Static Electricity, Current Electricity, Electromagnetic Waves, and Chemistry of Water. After the experimental trial period, an almost completely identical post-test evaluation was given to students in the same fashion to observe and compare gains in achievement. Test data was analyzed using an inferential statistics procedure that compared means and gains in knowledge made by the experimental and control groups. Difference between the gains of mean pre-test and post-test scores were statistically significant within each group, but were not statistically significant when the control and experimental groups were compared. Therefore, there was no clear practical effect. Qualitative data from teachers��� journals and students��� written feedback provides insight on the assessments, incorporation of the teaching method, and the development of participating students. Both mid and post-study student feedback shows that students had an overall positive and beneficial experience participating in this activity. Assessments and teacher journals showed areas of strength and weaknesses in student learning and on differences in teaching styles. They also helped support some feedback claims made by students. Areas of further research and improvement of the incorporation of this teaching method in the Basotho secondary science classroom are explored.