Modeling plasticity by non-continuous deformation

Plasticity and failure theories are still subjects of intense research. Yet, no compre-hensive theory has been achieved and the Molecular Dynamic method is far from providing a general model which contains only the essentials. This study is motivated by the observation that the continuum assumption in plasticity that neighbour material elements remain neigh-bours at all-time are physically impossible, since neighbour detachments, local slips and neighbour switching must operate, i.e., Non-Continuous Deformation (NCD). Material micro-structure is modelled by a set of point elements (particles) interacting with their neighbours. Each particle can detach from its neighbours and/or attach to a new neighbour during defor-mation. Simulations on two dimensional specimens subjected to uniaxial compression loading and unloading were conducted. Each specimen contained 100 particles with stochastic hetero-geneity controlled by a “disorder” parameter λ. It was found that a. the macro response is typ-ical to elasto-plastic behaviour; b. The number of detachments is linear with plastic energy; c. The number of attachments is linear with the residual strain, and d. Volume is preserved under plastic deformation. Rigid body displacement of local ensemble of elements was also ob-served. Higher disorder coefficient λ decreases the macro elastic modulus and increases the plastic energy

Regulation of haemopoietic stem‐cell proliferation in mice carrying the Slj allele

We investigated a haemopoietic stromal defect, in mice heterozygous for the Slj allele, during haemopoietic stress induced by treatment with bacterial lipopolysaccharides (LPS) or lethal total body irradiation (TBI) and bone‐marrow cell (BMC) reconstitution. Both treatments resulted in a comparable haemopoietic stem cell (CFU‐s) proliferation in Slj/+ and +/+ haemopoietic organs. There was no difference in committed haemopoietic progenitor cell (BFU‐e and CFU‐G/M) kinetics after TBI and +/+ bone‐marrow transplantation in Slj/+ and +/+ mice. the Slj/+ mice were deficient in their ability to support macroscopic spleen colony formation (65% of +/+ controls) as measured at 7 and 10 days after BMC transplantation. However, the Slj/+ spleen colonies contained the same number of BFU‐E and CFU‐G/M as colonies from +/+ spleens, while their CFU‐s content was increased. On day 10 post‐transplantation, the macroscopic ‘missing’ colonies could be detected at the microscopic level. These small colonies contained far fewer CFU‐s than the macroscopic detectable colonies. Analysis of CFU‐s proliferation‐inducing activities in control and post‐LPS sera revealed that Slj/+ mice are normal in their ability to produce and to respond to humoral stem‐cell regulators. We postulate that Slj/+ mice have a normal number of splenic stromal ‘niches’ for colony formation. However, 35% of these niches is defective in its proliferative support. Copyrigh

Journal Article – The Work of Psychologists in the Ninth Service Command Special Training Center

An article published in the March 1944 issue of the Psychological Bulletin, titled The Work of Psychologists in the Ninth Service Command Special Training Center that describes the Special Training Unit Program at military bases in the western United States.https://scholarworks.moreheadstate.edu/stu_1210th_fort_ontario/1059/thumbnail.jp

Middleborns disadvantaged? testing birth-order effects on fitness in pre-industrial finns

Parental investment is a limited resource for which offspring compete in order to increase their own survival and reproductive success. However, parents might be selected to influence the outcome of sibling competition through differential investment. While evidence for this is widespread in egg-laying species, whether or not this may also be the case in viviparous species is more difficult to determine. We use pre-industrial Finns as our model system and an equal investment model as our null hypothesis, which predicts that (all else being equal) middleborns should be disadvantaged through competition. We found no overall evidence to suggest that middleborns in a family are disadvantaged in terms of their survival, age at first reproduction or lifetime reproductive success. However, when considering birth-order only among same-sexed siblings, first-, middle-and lastborn sons significantly differed in the number of offspring they were able to rear to adulthood, although there was no similar effect among females. Middleborn sons appeared to produce significantly less offspring than first-or lastborn sons, but they did not significantly differ from lastborn sons in the number of offspring reared to adulthood. Our results thus show that taking sex differences into account is important when modelling birth-order effects. We found clear evidence of firstborn sons being advantaged over other sons in the family, and over firstborn daughters. Therefore, our results suggest that parents invest differentially in their offspring in order to both preferentially favour particular offspring or reduce offspring inequalities arising from sibling competition

A style discussion of Strange Quartet, Wits Trio Tribute, and Quin-tête-à-tête : three chamber works of Jeanne Zaidel-Rudolph composed between 2000-2019

The chamber works of Jeanne Zaidel-Rudolph encapsulate a world of stylised nuances. Yet, little has been written about these works, especially those composed after the year 2000. They portray a period in the composer’s compositional career during which she implemented an instinctive approach to composing. However, the composer’s compositional fingerprints permeate these works. This present study aims to analyse and present this style-producing syntax to better understand the composer’s chamber works and the compositional period during which these works were composed (post-2000). These style aspects are grouped and discussed according to the following topics: structure, melodic content, harmonic content, rhythm, and texture. These discussions provide valuable insights into Zaidel-Rudolph’s style, which include melodic writing based on pitch-class sets extracted from non-diatonic scales; interval preference; recurring harmonic structures comprising verticalized tri-, tetra-, and pentachords; quartal and quintal structures; split-member harmonies and added note chords; rhythmic structures expanded and modified to serve as motivic cohesion; and the utilisation of a rich diversity of textures to function as structure-contributing elements. Range and density factors also contribute to structure formation. This study incorporates multiple illustrative music examples and graphics to elucidate the discussed topics and aims to supply analytical information to performers, composers and analysts.Thesis (DMus (Composition))--University of Pretoria, 2021.UP DOCTORAL RESEARCH BURSARYMusicDMus (Composition)Unrestricte

Defining Archetypes and Requirements for mHealth Interventions in Rural Kenya: An Investigation in Collaboration with CURAFA™

Designing and implementing successful mobile health (mHealth) applications is always challenging, but even more so in countries and communities in rural areas where the target population have access to limited resources. While some mHealth initiatives have shown success and potential in Kenya, still too many fail. One of the reasons for failure is the limited understanding of the health-seeking behavior and social-technological context of the rural Kenyan population. This study aims to use a mixed-method approach to define archetypes of rural Kenyan patients and translate them into requirements which can guide the design and implementation of user-centric mHealth interventions in rural Kenya. With this study, we show how practitioners can leverage existing organizational and social structures in developing countries to develop mobile health applications tailored to patients’ needs

Contaminant mobilisation by fluid-rock interaction and related transport mechanisms in platinum tailings

Contaminant release and transport in platinum tailings are poorly studied in literature. This study serves to characterise these processes. The tailings facility is located in Steelpoort, Mpumalanga, South Africa on Critical Zone rocks of the Rustenburg Layered Suite in The Bushveld Igneous Complex. Tailings material samples were collected by hand auger- and direct push probe drilling at specific locations to represent the different materials present in the tailings facility. Water samples were collected from monitoring boreholes as well as the Steelpoort River. The samples were analysed using XRD, XRF, ABA, NAG, Reflected Light Microscopy, Acid Leaching Tests and ICP scans. Using the collected data, a geochemical model was constructed for the interpretation of mineral phase dissolution and to trace the mineral phases releasing contaminants. Analysis-, test- and modelling results showed that alteration mineral phases formed within ten years in the tailings material and that the existing alteration phases viz. talc and chlorite, as well as sulphides, are the major contributors of contaminants. Elevated pH values as well as major cation and anion concentrations were found in the fluid discharging from the tailings as well as the in groundwater, with little to no heavy metals, which were traced directly to the chromite phase. This suggests that platinum tailings do not contribute to heavy metal contamination or acid rock drainage but may increase aquifer salinity and alkalinity. The flow through the tailings, underlying vadose zone and fractured rock aquifer was characterised using permeameter- and pumping tests. From the data collected, an unsaturated flow model was developed to characterise the flow through the tailings. From the model, discharge from the tailings was calculated to take place at 0.7m per decade into the underlying vadose zone with fracture flow in the aquifer ranging from 0.46-0.026m/d, as calculated from pumping test results. Contaminant migration into the Steelpoort River is possibly inhibited by the Dwarsriver Fault, based on the chemical data and hydraulic conductivities calculated. Therefore, groundwater is considered to be the major receptor in the system and groundwater users may be negatively impacted by increasing groundwater salinity and major ion concentrations.Dissertation (MSc)--University of Pretoria, 2013.Geologyunrestricte

Supporting Subject Matter Experts as Developers: Towards a Framework for Decentralized Robotic Process Automation Development

Robotic Process Automation (RPA) has emerged as promising automation technology in recent years. Firms seize RPA for fast and cost-efficient low-code process automation implemented and maintained decentrally in the business units by subject matter experts (SMEs) without IT development experience. However, decentralized RPA projects are reported to frequently fail and be prone to challenges as SMEs struggle to meet their new roles and responsibilities, such as developers or testers. Yet, research lacks an understanding of how challenges related to SMEs' roles and responsibilities unfold and how to address these challenges when executing decentralized RPA projects. To this end, our study employs a Design Science Research approach, drawing on literature and 14 expert interviews, to (1) systematically synthesize the challenges related to SMEs' roles and responsibilities and (2) derive a software development framework for supporting SMEs in their new roles and responsibilities in decentralized RPA projects. Thus, our study contributes to RPA and low-code development research and provides SMEs with guidelines to navigate decentralized RPA projects in practice