Alien Registration- Roach, James (Old Town, Penobscot County)

https://digitalmaine.com/alien_docs/6023/thumbnail.jp

Dynamic Control of Network Level Information Processing through Cholinergic Modulation

Acetylcholine (ACh) release is a prominent neurochemical marker of arousal state within the brain. Changes in ACh are associated with changes in neural activity and information processing, though its exact role and the mechanisms through which it acts are unknown. Here I show that the dynamic changes in ACh levels that are associated with arousal state control informational processing functions of networks through its effects on the degree of Spike-Frequency Adaptation (SFA), an activity dependent decrease in excitability, synchronizability, and neuronal resonance displayed by single cells. Using numerical modeling I develop mechanistic explanations for how control of these properties shift network activity from a stable high frequency spiking pattern to a traveling wave of activity. This transition mimics the change in brain dynamics seen between high ACh states, such as waking and Rapid Eye Movement (REM) sleep, and low ACh states such as Non-REM (NREM) sleep. A corresponding, and related, transition in network level memory recall is also occurs as ACh modulates neuronal SFA. When ACh is at its highest levels (waking) all memories are stably recalled, as ACh is decreased (REM) in the model weakly encoded memories destabilize while strong memories remain stable. In levels of ACh that match Slow Wave Sleep (SWS), no encoded memories are stably recalled. This results from a competition between SFA and excitatory input strength and provides a mechanism for neural networks to control the representation of underlying synaptic information. Finally I show that during the low ACh conditions, oscillatory conditions allow for external inputs to be properly stored in and recalled from synaptic weights. Taken together this work demonstrates that dynamic neuromodulation is critical for the regulation of information processing tasks in neural networks. These results suggest that ACh is capable of switching networks between two distinct information processing modes. Rate coding of information is facilitated during high ACh conditions and phase coding of information is facilitated during low ACh conditions. Finally I propose that ACh levels control whether a network is in one of three functional states: (High ACh; Active waking) optimized for encoding of new information or the stable representation of relevant memories, (Mid ACh; resting state or REM) optimized for encoding connections between currently stored memories or searching the catalog of stored memories, and (Low ACh; NREM) optimized for renormalization of synaptic strength and memory consolidation. This work provides a mechanistic insight into the role of dynamic changes in ACh levels for the encoding, consolidation, and maintenance of memories within the brain.PHDNeuroscienceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147503/1/roachjp_1.pd

Synthesis And Photochemical Properties Of Some Porphyrin Derivatives

The initial step of photosynthesis involves transfer of an electron from a photo-excited porphyrin donor to a nearby ubiquinone acceptor. Compounds containing a porphyrin covalently linked to a benzoquinone have been shown to mimic this initial transfer and as such are useful models for the study of photo-induced intramolecular electron transfer. The first chapter of this thesis describes the synthesis of a linked porphyrin-benzoquinone species, designated P4Q. This compound consists of a tetra-aryl porphyrin linked cis-1,3 across a cyclobutane ring to a benzoquinone.;The photophysical properties of this compound and of two precursor species, the hydroquinone analog and the dimethoxy phenyl analog, designated as P4QH{dollar}\sb2{dollar} and P4DMB respectively, were measured in six solvents. The results indicate that intramolecular photo-induced electron transfer is possible in P4Q, and that relative to similar species it is surprisingly facile. The relatively fast observed rates for this electron transfer are rationalized in terms of the mediating role that the connecting linkage plays. The observed solvent effect on the rate of electron transfer was found to be consistent with Marcus theory.;The second and final chapter of this thesis outlines the attempted preparation of a water soluble porphyrin-cyclodextrin species and the attempts to determine complex dissociation constants for {dollar}\beta{dollar}-cyclodextrin-electron acceptor complexes in aqueous solution. This was an attempt to extend the use of {dollar}\beta{dollar}-cyclodextrin as a connecting linkage to aqueous solution. Cyclodextrins are useful as connecting linkages due to their ability to form inclusion complexes with a wide variety of species. This allows one porphyrin derivative, that linked to the cyclodextrin, to be used for screening several potential electron acceptors with a minimum of synthetic work. The attempts to measure the equilibrium dissociation constants were part of an attempt to quantify the kinetics of electron transfer in this system

Development of porous ceramic air bearings

Porous air bearings enjoy some important advantages over conventional air bearing types such as increased load carrying capacity, higher stiffness and improved damping. However, these types of bearings have yet to find widespread acceptance due to problems with obtaining materials with consistent permeability, instability issues relating to the volume of gas trapped at the bearing surface in the pores, and manufacturing the bearing without altering the permeability. Using a series of fine grades of alumina powder to minimise surface pore volume it has been demonstrated that it is possible to consistently and reproducibly manufacture porous bearings by injection moulding and slip casting. The relationship between powder size, processing conditions, porosity, mechanical properties and fluid flow characteristics were experimentally determined. The temperature of processing and the green density were found to be the controlling parameters in the resulting fluid flow properties for a given powder size, Test bearings were produced from the range of processing conditions investigated. It was found that the fine powder size bearings were stable over the entire range of test conditions irrespective of their initial manufacturing route. The most important consideration for the bearing performance was the quality of manufacture. The bearings were found to be sensitive to the flatness of their working surface and quality of fit in their test holder. The bearings were compared with published theories for load capacity and stiffness. A reasonable agreement was found with load carrying capacity once a correction for surface roughness was incorporated. Stiffness predictions provided a useful tool for the analysis and prediction of properties such as optimum values of permeability for a given geometry, if certain allowances are made

The case for negative senescence

Negative senescence is characterized by a decline in mortality with age after reproductive maturity, generally accompanied by an increase in fecundity. Hamilton (1966) ruled out negative senescence: we adumbrate the deficiencies of his model. We review empirical studies of various plants and some kinds of animals that may experience negative senescence and conclude that negative senescence may be widespread, especially in indeterminate-growth species for which size and fertility increase with age. We develop optimization models of life-history strategies that demonstrate that negative senescence is theoretically possible. More generally, our models contribute to understanding of the evolutionary and demographic forces that mold the agetrajectories of mortality, fertility and growth.

Michigan passenger rail: An analysis of community benefits

Passenger rail service is perceived to provide important benefits to Michigan communities. However, the extent of these benefits has never been quantified in a systematic way. The study reported on here involved the performance of a broad based assessment of the community level benefits of passenger rail serv ice. The main objective of the research project was to estimate the full range of these benefits at the community level, as opposed to at the state level. Benefits were estimated for individual travelers, Amtrak expenditures, and local businesses. This research indicates local communities currently realize $62.0 million annually in benefits. Additional benefits accrue to the region, state, and nation in the form of congestion relief, air quality improvement, energy conservation, and safety

MIS versus Computer Science: An Empirical Comparison of the Influences on the Students’ Choice of Major

A history of declining enrollments in university Management Information Systems (MIS) and computer science (CS) departments in the U.S. considerably impacts both college departments and business organizations that hire graduates. In order to reverse the enrollment trend, an understanding of the important similarities and differences that shape a student’s decision to major in MIS or CS will allow departments to better promote their major, formulate more effective strategies for reaching interested and undecided students, and enhance the fit between student and career. This study directly compared important influences on choice of major for 205 MIS and CS majors at four US universities. Results indicate that the most important influences for both MIS and CS students are interest in technology and monetary compensation. MIS majors, however, are significantly more influenced by others, especially college instructors, parents, friends, and the desire to interact with others. They are also more interested in business and business organizations. CS majors, on the other hand, are more interested in the technology itself and tend to choose CS as a major either in high school or shortly thereafter. Based on these findings, recommendations are provided to aid college departments in attracting and retaining appropriate majors

Generational Impacts of 1930s Housing Discrimination and the Imperative Need for the Healthy Start Initiative to Address Structural Racism

For nearly three decades, Healthy Start Initiative(HSI) has served communities with high rates of adverse pregnancy outcomes--with the goal to lower them by 50%. Despite a large focus on social determinants of health, HSI has narrowly addressed racism. The effects of legal housing discrimination continue to be felt and have profound implications for pregnancy. To understand the historical context of racism in these communities, we geospatially evaluated the relationship between HSI service areas and Home-Owners Loan Corporation(HOLC) graded maps. Using data from John Snow Inc, National Healthy Start Association, and Mapping Inequality we found that 73 of 100 communities served by HSI were subject to anti-Black housing discrimination. For majority, over 60% of the HOLC-assessed areas in the service areas were red or yellow graded. Given this we propose three programmatic shifts that HSI can implement to address structural racism and broaden their policy and advocacy efforts in the communities they serve