Thesis (Psy. D.)--Wheaton College Graduate School, 2007. / Abstract. Includes bibliographical references (leaves 35-40).

Abstract Branches of adult Scots pine (Pinus sylvestris L.) trees were sampled from boreal dry pine forests to study needle longevity, its variation and its relation to other shoot characteristics. The stands studied were located along transects from two smelters and one city, e.g. along gradients of pollution impact. Constant needle age structures were assumed and static life-tables generated. Mean needle longevity was calculated as the sum of the proportions of living needle fascicles on the successive annual shoots. It fully incorporated the information of the static life-tables and was preferred to median or maximum ages because of its significantly lower variation. The first half of the shedding span, the duration of the period when the needle survival gradually dropped from 90 to 50 %, proved to validly reflect the changes in the needle age structure. Needle longevity decreased 15-40 % towards the pollution sources along the transects studied. Near the smelters, needle longevity decreased with the increasing needle Fe, or Fe, Ni and Cu concentration that represented the main constituents of the airborne particle emissions. Near the city, needle longevity decreased with the increasing needle N and P concentrations, annual needle mass and needle mass packing and decreasing needle area packing. In the urban forests, needle Mg, P and K concentrations decreased linearly with the decreasing needle survival from the second to the fourth needle age class. Concentrations in the living needles of the fourth age class stayed over 80 % of the average for all the age classes, though needle survival dropped below 50 %. A decreasing needle Mn concentration was detected towards all the emission sources. Leaching, especially from the soil, as a possible cause was discussed. Needle longevity had the lowest variation among the shoot characteristics, which increases its value as a tool in ecological monitoring. Low plasticity in needle longevity could be an acclimation to the ambient environmental conditions and length of the growing season and to maximise the carbon gain per time. Needle longevity decreased and annual needle mass and leaf mass per area increased upwards in the crowns of mature Scots pines, reflecting the acclimation to irradiance.

Paperboard combined with polymer and aluminium films are widely used in food packages. Paperboard is used for the bulk of the package material, and provides the stiffness. Paperboard is a highly anisotropic material, which is affected by how the fibers are orientated. Most fibers are aligned in the machine direction (MD), which is the stiffest direction, perpendicular is the cross-machine direction (CD) where fewer fibers are aligned, and the thickness direction (ZD) which is considerably weaker than in the MD and CD directions. Continuum models are used to describe the material properties to aid the design of package manufacturing processes. In continuum models there are no inherent length scale effects, and the material behaviour is the same regardless of the geometry. For paperboard there have been experimentally observed effects of the gauge length and width of tensile tests. To calibrate and develop these models it is important to observe which effect is a material property, if there is an inherent length scale, and which properties are from the boundary conditions of the experimental setup. Creasing is a process where the length scale is considerably smaller than at the standard tensile test, where the material deforms plastically to create creasing lines to easier fold the paperboard. The failure properties from standard tensile tests are not a good predictor of failure in creasing, where the length scale is considerably smaller. To investigate if there is an effect of the length scale, as the length gets smaller, tensile tests have been performed at different gauge lengths. The tensile tests were performed with a width of 15mm and the gauge length was varied in the range 3-100mm in MD and CD. The results from the tensile tests were, the failure strain and failure stress increased as the gauge length of the tests specimens decreased, both in MD and in CD. Initial stiffness decreased as the gauge length decrease (more notable in MD), and there was an increase in hardening at large strains with decreasing gauge length (more notable in CD). An analytical calculation of the reduction in measured stiffness as the gauge length get smaller was performed, where the decrease in stiffness deemed to be strongly related to the out-of-plane shear modulus. By fitting the analytical solution the experimental data the shear modulus was approximated to 60MPa. The shear modulus has been measured for the same paperboard to 70±23MPa. Simulations of the tensile tests at 5mm did fit the experimental data when the material model was calibrated from the tensile test at 100mm, except the increase in hardening at large strains in CD. It was noted that it was important to use the shear modulus that was inversely calculated by the analytical calculations to get the right initial slope of the simulations of the 5mm tensile tests. Creasing simulations were performed of a test setup of the creasing procedure. The male die was lowered 0.3mm to perform the creasing, which in the tests setup do not result in failure in the material. From the simulations the stress at the bottom of the paperboard during creasing exceeded the failure stress from the tensile test performed at 100mm. The stress during creasing was biaxial, it has stresses both in MD and CD, with is different compared to the uniaxial tensile tests at 100mm. The stress from the creasing simulation in CD was at a maximum of 40MPa where the 3mm tensile tests in CD resulted in a failure stress at 39MPa. The maximum stress in the MD creasing simulation was 96MPa, where the 3mm tensile test resulted in a failure stress at 69MPa. The properties from a long span tensile test are not good predictors of failure in creasing, where both stress state and length scale are very different. The failure stress at 3mm tensile tests in CD is close to the maximum stress from creasing simulations, and may be a good indication of failure. The 3mm tensile test in MD resulted in a considerably lower failure stress than the maximum stress in the creasing simulations, which indicates that the 3mm long tensile test is not a good predictor of failure in MD for creasing, where the length scale is even smaller.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Yes

Yes / Living longer without simultaneously extending years spent in good health ("health span") is an increasing societal burden, demanding new therapeutic strategies. Hydrogen sulfide (H2S) can correct disease-related mitochondrial metabolic deficiencies, and supraphysiological H2S concentrations can pro health span. However, the efficacy and mechanisms of mitochondrion-targeted sulfide delivery molecules (mtH2S) administered across the adult life course are unknown. Using a Caenorhabditis elegans aging model, we compared untargeted H2S (NaGYY4137, 100 µM and 100 nM) and mtH2S (AP39, 100 nM) donor effects on life span, neuromuscular health span, and mitochondrial integrity. H2S donors were administered from birth or in young/middle-aged animals (day 0, 2, or 4 postadulthood). RNAi pharmacogenetic interventions and transcriptomics/network analysis explored molecular events governing mtH2S donor-mediated health span. Developmentally administered mtH2S (100 nM) improved life/health span vs. equivalent untargeted H2S doses. mtH2S preserved aging mitochondrial structure, content (citrate synthase activity) and neuromuscular strength. Knockdown of H2S metabolism enzymes and FoxO/daf-16 prevented the positive health span effects of mtH2S, whereas DCAF11/wdr-23 - Nrf2/skn-1 oxidative stress protection pathways were dispensable. Health span, but not life span, increased with all adult-onset mtH2S treatments. Adult mtH2S treatment also rejuvenated aging transcriptomes by minimizing expression declines of mitochondria and cytoskeletal components, and peroxisome metabolism hub components, under mechanistic control by the elt-6/elt-3 transcription factor circuit. H2S health span extension likely acts at the mitochondrial level, the mechanisms of which dissociate from life span across adult vs. developmental treatment timings. The small mtH2S doses required for health span extension, combined with efficacy in adult animals, suggest mtH2S is a potential healthy aging therapeutic. / A.R.V., M.W., and T.E. were supported by the US Army Research Office (W911NF-19-1-0235). L.S., M.W., and T.E. were supported by the United Mitochondrial Disease Foundation (PI-19-0985). L.S. was also supported by the University of Exeter Jubilee Scholarship. M.C., N.J.S., and T.E. were supported by the UK Space Agency (ST/R005737/1). N.J.S. and T.E. were supported by BBSRC (BB/N015894/1). S.A.V. was supported by NASA (NNX15AL16G). N.J.S. was supported by grants from NASA [NSSC22K0250; NSSC22K0278] and acknowledges the support of the Osteopathic Heritage Foundation through funding for the Osteopathic Heritage Foundation Ralph S. Licklider, D.O., Research Endowment in the Heritage College of Osteopathic Medicine.

This investigation was conducted to study the bump and airblast problems associated with delayed caving of competent longwall roofs. The roofs were modeled as elastic beams on continuous elastic foundations subject to exponentially distributed abutment stress. Elastic beam theory was applied to develop analytical solutions for deflection of single-layer roof models. Methods for analyzing double-layer roof and double-layer foundation models are discussed. Formulae for evaluating critical spans of the roof beds and strain energy storage in the roof and foundation are developed. The factors affecting roof caveability and energy accumulation are identified and analyzed. A comprehensive parametric analysis reveals that mechanical characteristics of roof beds, “foundation properties, abutment stress concentrations, and roof configurations may interact to influence roof caveability and energy storage. Based on estimation of local Richter magnitude, criterion for pressure and shock bump events are suggested. Five case studies of bump events show that the theoretical predictions agree well with field data. The developed model solutions were implemented in a Windows-based software package CBPEP. This package facilitates determination of roof spans, stored strain energy in the roof and foundation, and the coal bump potential caused by delayed caving of strong roofs. The increases in air pressure and temperature associated with sudden roof collapse in a large area was also investigated using an adiabatic air compression model. The presence of fragmented gob materials on the floor greatly influences the pressure and temperature variations after the recompaction of fragmented material commences. Three case studies of airblasts were analyzed, one of which was associated with a mine explosion. The investigation indicates that when a sufficiently large collapse is anticipated in a mine where flammable gas or dust may be present, it should be assumed that there exists a possibility that the high air pressure and temperature induced could trigger an explosion. / Ph. D.

The life span of facilities produced by the Architecture-Engineering-Construction industry is typically 25 years or more Several distinct phases characterize the life span of a facility. Each of these phases involve numerous participants from different professional disciplines. These participants generate and use a lot of information about the facility. Current methods used by the industry to convey this information are drawings and specifications. However. these drawings and specifications reflect only a summary of the information generated and used by the project participants This summarized information only describes the product. Information about the process of generating these information becomes implicit in the drawings and specifications. Rationale is the collective term for this set of implicit process information. The main issue addressed by this dissertation is the need to communicate design rationale information. Design rationale is a subset of the entire rationale generated for a facility Design rationale refers to information about the design process. Explicitly stating design rationale information reduces the chance of misinterpreting design drawings and specifications. The primary objective of this dissertation is to determine a data structure capable of representing design rationale information. This data structure also allows a computer system to perform analytical tasks on the design rationale data. Examples of analytical tasks a computer system can perform on design rationale data include: generating a parameter dependency network and resolving data conflicts. This dissertation defines this data structure as two separate but complementary modules. The Knowledge Representation Module assists in gathering project-specific product information. The Rationale Storage Module assists in capturing project-specific process information. This dissertation discusses each of these two modules in detail. The secondary objectives of this dissertation include: (1) defining a computer program architecture, (2) creating a computer program interface, and (3) verifying the appropriateness of the data structure in representing design rationale. A proof-of-concept computer program, DRIVE, applied to an actual value engineering study project accomplishes these objectives. / Ph. D.

The Morton Effect in the rotor - bearing systems may lead to an unstable operation. Up to the present, most of the established research efforts have been focused on the overhung rotor systems. In this dissertation, a systematic study on the Morton Effect induced instability in mid-span rotor systems is presented. First, the mechanism study is conducted. The simplified rotor models with isotropic linear bearing supports are adopted for the derivation of analytical expressions. The threshold speeds of instability in simple forms are obtained for the systems with the thermal imbalance acting concurrent with or perpendicular to the direction of the response displacement. For a perspective view of the system stability, a stability map for the damped rigid mid-span rotors with the thermal imbalance having arbitrary phase difference has been generated. It shows that the stable operating regions of the system are bounded by two curves of threshold of instability. The results show that the Morton Effect induced instability thresholds are actually affected by both the magnitude and relative phase of the thermal imbalance. The mechanism of the Morton Effect induced thermal instability of mid-span rotors supported by linear isotropic bearings can be explained through the fact that the Morton Effect introduces either negative stiffness or negative cross-coupled stiffness. Next, the steady-state response performance under the influence of the Morton Effect is discussed. The results show that the Morton Effect has a comprehensive impact on both the amplitude and phase lag of the steady-state unbalance response. It may shift both curves in a manner dependent on the relative magnitude and direction of the thermal imbalance. Then, the mid-span rotors supported by the hydrodynamic journal bearings are analyzed. The models to calculate the thermal bending of the shaft and the temperature distribution across the journal surface are established. The calculations of the temperature difference and its equivalent thermal imbalance are conducted and discussed with the comparison to the analytical results. It shows that the thermal imbalance may increase to the level of the mechanical imbalance and its influence on the system stability should be then included. The suggested thermal bending model also explains that the mid-span rotors are less liable to be influenced by the Morton Effect than are the overhung configurations, because of the restraining effect between the two supports. The simulation results of a symmetric mid-span rotor - hydrodynamic journal bearing system show that the inclusion of the Morton Effect may lead to an unstable operation of the system. Considering the existence of the oil film self-induced vibration due to the dynamic characteristics of fluid film bearings, the Morton Effect may make a further negative impact on the instabilities of the rotor system under some working conditions. Finally, the predictive solution method for the general mid-span rotors is discussed. The computer code, VT-MAP, is developed for the predictions of the Morton Effect induced instability of rotor systems in either mid-span and overhung configurations. / Ph. D.

There has been little research exploring whether different memory processes (i.e. related to short term memory (STM), working memory (WM) and long term memory (LTM) may be differentially sensitive to representation and processing aspects of compound words. This study investigated how compound words are represented in STM in immediate serial recall tasks and in WM in complex span tasks that combine processing and storage demands. The simple span STM task was comprised of solely a list of memory words, whereas the two complex span WM tasks interleaved sentence processing between presentation of memory words. They varied in the presence of a pause after presentation of each memory word and before onset of the following distractor sentence for processing. The absence of a pause was intended to minimize opportunity for subvocal rehearsal, whereas the presence of a pause encouraged rehearsal. To increase chances of recombination errors for error analyses, lists of memoranda were manipulated so that each set (list) of four compound words contained one “lure” pair (e.g. pinstripe + warhead = pinhead) in which the modifier and head constituents from separate compound words could recombine to form a new, legal word. Recall performance was better in the simple span and complex span pause tasks compared to the complex span no pause task. Whole compound and left constituent frequencies played opposite roles, helping and harming, respectively. Error types reflecting decomposition of the compound words to their constituents were more common in simple span than in complex span. Omissions were more common in complex span. We discuss how different memory processes may be differentially sensitive to representation and processing aspects, and how recall of compound words is affected by various lexical variables. / Thesis / Master of Science (MSc)