Digital Commons Network^™

Synthesis And Fundamental Characterization Of Nanoparticles And Their Clusters, Ke Du

Dissertations

Nanoparticles of gold derivatized with monolayers of thiocarboxylic acid ligands, core/shell nanoparticle composites of gold and silica, gold-glutathioneclusters, and titania nanoparticles were synthesized and their surface properties (extent of ligand coverage, net negative charge, and zeta potential) characterized by capillary electrophoresis as a function of pH, ionic strength, and dielectric constant for the first time. The hydrodynamic radii of thenanoparticles were determined by dynamic laser light scattering and used to calculate the net surface charge, extent of ligand coverage, and zeta potentials ofthe nanoparticles from electrophoresic mobilities. The ligand derivatized nanoparticles had similar hydrodynamic radius of about 20 nm which …

Retaining Information Technology Employees In Higher Education, Mary Holmes

Dissertations

The retention of qualified Information Technology (IT) employees is at an all time low within higher education institutions. IT personnel are essential for higher education institutions to effectively integrate technology into their educational programs. These IT employees contribute to their institution's teaching/learning mission, while simultaneously supporting complex and highly visible administrative operations. Yet, all previous research regarding IT employee retention issues had only been conducted within corporate settings.

To examine factors related to IT employees' retention within public higher education, an internet-based study was sent to IT employees in all four-year public universities throughout Michigan. The survey included questions within …

Investigation Of Oxy-Anion Legand Adsorption Onto Surfaces Of Iron Oxide And Bacteria In Groundwater Aquifers, Haile Mengistu

Dissertations

We have measured adsorption of dissolved phosphate onto synthetic hydrous ferric oxide (HFO), dissolved arsenate and chromate onto the cell membrane of a bacterium species, S. putrefaciens as a function of pH, ionic strength, and relative concentrations of the respective oxy-ligands. Our experimental data were used to constrain optimal values for surface complexation reactions involving dissolved oxi-ligands (phosphate, and chromate) and the HFO surface and the cell membrane of S. putrefaciens respectively according to the diffuse layer model.

Our results provide a more accurate fit to experimental measurements over a broader range of pH (3 - 12), ionic strength and …

New Tests Of Univariate Symmetry Based On The Gini Mean Difference, Hend Ouda

Dissertations

Gini mean difference (GMD) was proposed as a measure of income inequality by Corrado Gini in 1912. Since then it has been widely applied - mostly in theeconomics, but also in statistical and social science research.

Four statistical tests of univariate symmetry are being proposed---all based on the comparison of variation below and above the median (known or estimated) measured by the GMD. These tests are applicable to the data from populations with median known and unknown, and each of them has its rank-basedcounterpart, so they can also be used for ordinal data.

A Monte Carlo simulation study was performed …

The Effect Of Using A Video-Case Curriculum To Promote Preservice Teachers’ Development Of A Reflective Stance Towards Mathematics Teaching, Shari L. Stockero

Dissertations

This study investigates the effects of using a coherent video-case curriculum in a university methods course. In particular, three issues are addressed: (1) howthe use of a video-case curriculum affects the reflective stance of preservice teachers; (2) the extent to which a reflective stance developed while reflecting on other teachers' practice transfers to reflecting on one's own practice; and (3) how preservice teachers' reflective stance that is developed via sustained and focused reflection using a video-case curriculum compares to the reflective stance of peers who engaged in less sustained and focused reflection. Althoughvideo cases are increasingly being used in teacher …

A Distributed Hierarchical Energy-Efficient Scheme For Large Scale Mobile Wireless Ad Hoc Networks, Wasim El Hajj

Dissertations

In recent years, wireless networks have enjoyed tremendous development and popularity due to the technological advances of wireless radio devices. While interest in conventional wireless networks continues to evolve, new types of wireless networks, such as Mobile Ad Hoc Networks (MANET) and WirelessSensor Networks (WSN) are evolving fast and receiving much attention from academia, industry, and government.

Scalability and energy-efficiency present two of the most important challenges in Mobile Ad Hoc Networks. Scalability in MANETs can be defined as the capability of the network to provide an acceptable throughput when the network size increases. Energy-efficiency can be defined as using …

Detectable Coloring Of Graphs, Henry E. Escuadro

Dissertations

A basic problem in graph theory is to distinguish the vertices of a connected graph from one another in some manner. In this study, we investigate the problemof coloring the edges of a graph in a manner that distinguishes the vertices of the graph. The method we use combines many of the features of previously introduced methods.

Let G be a connected graph of order n ≥ 3 and let c : E (G ) [arrow right] {1,2,...,k } be a coloring of the edges of G (where adjacent edges may be colored the same). For each vertex …

Testing Procedures For Group Sequential Clinical Trials With Multiple Survival Endpoints, Rebecca C. Scherzer

Dissertations

This research gives methods for sequential monitoring of survival data in clinical trials with multiple endpoints. We illustrate the use of marginal proportional hazards models and other survival models with various group sequential methods to test multiple survival endpoints at K interim analyses. To adjust for multiplicity at each interim analysis, we consider and extend methods developed by Tang and Geller (1999), Follmann, et al. (1994), and others. These methods are motivated, compared, and evaluated using survival data from a clinical study and using simulation studies.

New Estimators Of A Circular Median, Sauwanit Ratanaruamkarn

Dissertations

The specific properties of probability distributions on a circle require different definitions of several statistical concepts. For example, a median that can always be found for linear data not always exists on the circle. Several estimators of a circular median were proposed, lately by Otieno (2002), Otieno and Anderson - Cook (2003). Their work is, however, focused on the "preferred direction" which coincides with the median, mean and mode in the case of symmetric, unimodal distributions. This dissertation is focused on the estimators of a population median in a wider range of population distributions on a circle including distributions with …

Synthetic Studies Of 1,10-Phenanthroline Derivatives As Novel Catalysis Ligands And Their Application In Transition Metals Catalyzed Reactions, Son Duc Tran

Dissertations

The preparation of 1,10-phenanthroline derivatives entailed ring opening reactions of 1,10-phenanthroline epoxide as a key transformation, affording novelbidentate nitrogen ligands with new stereogenic centers in the 5- and 6-position. This research was concerned with (i) the epoxidation of 1,10-phen, (ii) epoxide ring opening reactions, (iii) the formation of trans -5,6-disubstituted-1,10-phenanthroline metal complexes, and (iv) application of 1,10-phenanthroline derivatives in metal-catalyze reactions such as palladium-catalyzed allylic substitution and aminohalogenation reactions; Zinc-catalyzed direct aldolreaction, and acetophenone reduction; Nickel-catalyzed Michael addition reaction.

Nilpotent Orbits On Infinitesimal Symmetric Spaces, Joseph A. Fox

Dissertations

Let G be a reductive linear algebraic group defined over an algebraically closed field k whose characteristic is good for G. Let [straight theta] be an involution defined on G, and let K be the subgroup of G consisting of elements fixed by [straight theta]. The differential of [straight theta], also denoted [straight theta], is an involution of the Lie algebra [Special characters omitted.] = Lie (G ), and it decomposes [Special characters omitted.] into +1- and -1-eigenspaces, [Special characters omitted.] and [Special characters omitted.] , respectively. The space [Special characters omitted.] identifies with the tangent space at the …

Localization In Wireless Sensor Networks, Mark Terwilliger

Dissertations

With the proliferation of wireless sensor networks, providing location-aware technology and services to new applications have become important for developers. Localization is the problem of determining the positions of nodes in an ad hoc network. With the constrained resources of network sensors, providing robust localization services remains a fundamental research challenge facing the entire sensor network development community.

The initial localization problem that we addressed was to design and develop a working system that could locate equipment, such as a laptop or video projector. Ferret, the localization system developed, uses two different ranging techniques to help locate an object to …