Reduction of cure-induced stresses in thermoset polymer composites via chemical and thermal methods

This thesis discusses three different experiments in which we examine in-cure residual stresses in carbon/epoxy thermoset polymer composites. Throughout this research the Cure Induced Stress Test (CIST), developed at UT, has been used. The CIST is a unique experimental procedure in which the effect of polymer volume change on fiber stress is determined by monitoring the change in fiber load. In the first part of the research, we addressed the role of fiber-matrix interface on the fiber-load measurement. For this purpose, the CIST experiments were conducted with as-received and Teflon-coated fibers. The Teflon coating was intended to weaken the fiber-matrix interface. The use of a Teflon coating was shown to have no effect on the fiber load measurements during cure. Thus, it is concluded that the fiber-matrix interface does not significantly influence the data obtained in the CIST experiments. Second, we use CIST to verify a new methodology to reduce the internal stresses involving a chemically engineered ring-opening reaction that is still under development. The purpose of the ring-opening reaction is to offset the polymer shrinkage. Finally, we use CIST to expand upon a previous study to determine the build-up of polymer stiffness during cure. Comparison of stiffness curves obtained from CIST and measured stiffness values of fully and partially cured polymer samples show a good agreement

Identity Selection and the Social Construction of Birthdays

We argue that rather than being a wholly random event, birthdays are sometimes selected by parents. We further argue that such effects have changed over time and are the result of important psychological processes. Long ago, U.S. American parents greatly overclaimed holidays as their children’s birthdays. These effects were larger for more important holidays, and they grew smaller as births moved to hospitals and became officially documented. These effects were exaggerated for ethnic groups that deeply valued specific holidays. Parents also overclaimed well-liked calendar days and avoided disliked calendar days as their children’s birthdays. However, after birthday selection effects virtually disappeared in the 1950s and 1960s, they reappeared after the emergence of labor induction and planned cesarean birth. For example, there are many fewer modern U.S. births than would be expected on Christmas Day. In addition, modern parents appear to use birth medicalization to avoid undesirable birthdays (Friday the 13th). We argue that basking in reflect glory, ethnic identity processes, and superstitions such as magical thinking all play a role in birthday selection effects. Discussion focuses on the power of social identity in day-to-day judgment and decision-making

Public art today. How public art sheds light on the future of the theory of commons

Public art and common goods, although belonging to apparently distant realms of inquiry, share a long history and, inevitably, an evolving meaning. This chapter investigates the evolution of the practice of public art with the objective to obtain a viable understanding of how the value of public art is produced today. With a focus on the future of public art, this chapter investigates three public art cases. The results of the qualitative analysis of these public art experiences are interpreted from an institutional economics perspective. The combination of public art and the theory of commons sheds light on what seems to be the most important attributes of common goods in the current debate, that is the social practices that constitute the act of making the commons.</p

Social comparison processes in organizations

We systematically analyze the role of social comparison processes in organizations. Specifically, we describe how social comparison processes have been used to explain six key areas of organizational inquiry: (1) organizational justice, (2) performance appraisal, (3) virtual work environments, (4) affective behavior in the workplace, (5) stress, and (6) leadership. Additionally, we describe how unique contextual factors in organizations offer new insight into two widely studied sub-processes of social comparison, acquiring social information and thinking about that information. Our analyses underscore the merit of integrating organizational phenomena and social comparison processes in future research and theory

REVEILLE8 and PSEUDO-REPONSE REGULATOR5 Form a Negative Feedback Loop within the Arabidopsis Circadian Clock

Circadian rhythms provide organisms with an adaptive advantage, allowing them to regulate physiological and developmental events so that they occur at the most appropriate time of day. In plants, as in other eukaryotes, multiple transcriptional feedback loops are central to clock function. In one such feedback loop, the Myb-like transcription factors CCA1 and LHY directly repress expression of the pseudoresponse regulator TOC1 by binding to an evening element (EE) in the TOC1 promoter. Another key regulatory circuit involves CCA1 and LHY and the TOC1 homologs PRR5, PRR7, and PRR9. Purification of EE–binding proteins from plant extracts followed by mass spectrometry led to the identification of RVE8, a homolog of CCA1 and LHY. Similar to these well-known clock genes, expression of RVE8 is circadian-regulated with a dawn phase of expression, and RVE8 binds specifically to the EE. However, whereas cca1 and lhy mutants have short period phenotypes and overexpression of either gene causes arrhythmia, rve8 mutants have long-period and RVE8-OX plants have short-period phenotypes. Light input to the clock is normal in rve8, but temperature compensation (a hallmark of circadian rhythms) is perturbed. RVE8 binds to the promoters of both TOC1 and PRR5 in the subjective afternoon, but surprisingly only PRR5 expression is perturbed by overexpression of RVE8. Together, our data indicate that RVE8 promotes expression of a subset of EE–containing clock genes towards the end of the subjective day and forms a negative feedback loop with PRR5. Thus RVE8 and its homologs CCA1 and LHY function close to the circadian oscillator but act via distinct molecular mechanisms

The impact of language barriers on trust formation in multinational teams

This study systematically investigates how language barriers influence trust formation in multinational teams (MNTs). Based on 90 interviews with team members, team leaders, and senior managers in 15 MNTs in three German automotive corporations, we show how MNT members’ cognitive and emotional reactions to language barriers influence their perceived trustworthiness and intention to trust, which in turn affect trust formation. We contribute to diversity research by distinguishing the exclusively negative language effects from the more ambivalent effects of other diversity dimensions. Our findings also illustrate how surface-level language diversity may create perceptions of deep-level diversity. Furthermore, our study advances MNT research by revealing the specific influences of language barriers on team trust, an important mediator between team inputs and performance outcomes. It thereby encourages the examination of other team processes through a language lens. Finally, our study suggests that multilingual settings necessitate a reexamination and modification of the seminal trust theories by Mayer, Davis and Schoorman (1995) and McAllister (1995). In terms of practical implications, we outline how MNT leaders can manage their subordinates’ problematic reactions to language barriers and how MNT members can enhance their perceived trustworthiness in multilingual settings