An investigation of sampled data interpolation error

Ph.D.D. L. Fin

Representatives of similarity classes of matrices over PIDs corresponding to ideal classes

For a principal ideal domain A, the Latimer–MacDuffee correspondence sets up a bijection between the similarity classes of matrices in Mn(A) with irreducible characteristic polynomial f(x) and the ideal classes of the order A[x]/(f(x)). We prove that when A[x]/(f(x)) is maximal (i.e. integrally closed, i.e. a Dedekind domain), then every similarity class contains a representative that is, in a sense, close to being a companion matrix. The first step in the proof is to show that any similarity class corresponding to an ideal (not necessarily prime) of degree one contains a representative of the desired form. The second step is a previously unpublished result due to Lenstra that implies that when A[x]/(f(x)) is maximal, every ideal class contains an ideal of degree one

The Impact of Land Tenure on Food Security of Indigenous Communities

How does land tenure and security-- the legal rights to land and defense of property— impact the food security of Indigenous communities? Indigenous communities throughout Latin America often depend on the land to meet their basic food and water needs. Recently, arable land and natural resources have become more important due to the 2008 recession and fears of an impending food crisis (Borras et al, 2012). Agricultural corporations, states, and other entities have actively begun buying or renting large swaths of land classified as ‘under-utilized’ or ‘unoccupied’ from countries and institutions willing to conduct business (Araya, 2019; Ashukem, 2020; Borras et al, 2012; Aguilar-Støen, 2016; Bebbington and Bebbington, 2009). This has increased land insecurity in many parts of the region due to an increase in competing claims over resource rich lands, often spaces inhabited by Indigenous populations.Scholars have found that land tenure and security can impact cultural practices, spirituality, and mental health, which may permanently alter how Indigenous communities subsist in the region (Hinchman and Hinchman, 1998). While the body of literature examining land tenure’s impact on mental health and spirituality is growing (e.g, Hagen and Minter, 2019), to date little research has evaluated land tenure’s effects on food security of Indigenous and rural communities in Peru. This brings us back to the research question at hand: What are the food security implications of informal land tenure on Indigenous communities? What framework for implementing land tenure proves to be better for Indigenous communities and their food security

Racializing Experiences of Foreign-Born and Ethnically Diverse Black Male Engineering Graduate Students: Implications for Student Affairs Practice, Policy, and Research

Despite a growing body of work on the experiences of Black collegians, the higher education knowledge base lacks scholarship focused on Black men in graduate programs who are foreign-born and/or identify ethnically as other than African American. In this article, we provide a domain-specific investigation (i.e., based on students’ field of study), centering on nine Black men in engineering graduate programs. Three themes emerged regarding students’ racialized experiences and effects of racialization: (1) racialization as a transitional process; (2) cultural identity (dis)integrity; and (3) racialized imposter syndrome. We conclude with implications for developing and implementing promising practices and activities that aid students throughout graduate school. Such targeted efforts might also improve the likelihood of students remaining in the engineering workforce

An ultrafast thermal emission spectrometer for investigating temporal thermal emission of metal thin-films and their reactive derivatives

An experimental system was constructed for studying the reaction of nanolaminate thermites in both the temporal and spectral domains. 1mJ pulses from a Ti:Sapphire laser, stretched to 10ps, were focused onto sample films affixed to glass slides. The emission generated by the ablation of the films was collected and focused into a spectrograph and subsequently directed into a Hamamatsu C4334 streak device. It was found that this system was capable of providing spectral and temporal information from the emission of ablated metal and thermite nanolaminate films over a timescales ranging from tens of nanoseconds to milliseconds

Bubble-Driven Inertial Micropump

The fundamental action of the bubble-driven inertial micropump is investigated. The pump has no moving parts and consists of a thermal resistor placed asymmetrically within a straight channel connecting two reservoirs. Using numerical simulations, the net flow is studied as a function of channel geometry, resistor location, vapor bubble strength, fluid viscosity, and surface tension. Two major regimes of behavior are identified: axial and non-axial. In the axial regime, the drive bubble either remains inside the channel or continues to grow axially when it reaches the reservoir. In the non-axial regime the bubble grows out of the channel and in all three dimensions while inside the reservoir. The net flow in the axial regime is parabolic with respect to the hydraulic diameter of the channel cross-section but in the non-axial regime it is not. From numerical modeling, it is determined that the net flow is maximal when the axial regime crosses over to the non-axial regime. To elucidate the basic physical principles of the pump, a phenomenological one-dimensional model is developed and solved. A linear array of micropumps has been built using silicon-SU8 fabrication technology, and semi-continuous pumping across a 2 mm-wide channel has been demonstrated experimentally. Measured variation of the net flow with fluid viscosity is in excellent agreement with simulation results.Comment: 18 pages, 18 figures, single colum