Combined dilatometry and mass spectrometry of sintering and evolved gases of barium titanate and zirconium diboride with sintering additives

Title from PDF of title page (University of Missouri--Columbia, viewed on March 8, 2013).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Thesis advisor: Dr. Stephen J. LombardoIncludes bibliographical references.M. S. University of Missouri--Columbia 2012."December 2012"A combined dilatometer mass spectrometer system (CDMS) is used to monitor the gas phase species and sintering progress in real time during the heating of barium titanate and ultra high temperature ceramics (UHTCs), including zirconium diboride and sintering additives. For loose powder and pressed samples of barium titanate heated at different rates, two families of signals were observed by mass spectrometry at mass to charge (m/z) ratios of 44 and 64 prior to the onset of sintering at 1150[degrees]C, and were assigned as carbon dioxide and sulfur dioxide. The sources for carbon dioxide and sulfur dioxide evolution include organic impurities arising from processing, exposure to ambient organic material, adsorbed carbon dioxide and residual unreacted or surface barium carbonate and barium sulfate. The UHTCs and common sintering aids heated in the CDMS individually and in mixtures include zirconium diboride, boron carbide, silicon carbide, boron oxide, zirconium oxide, zirconium disilicide, boron nitride spray, and organic binder, dispersant, and surfactant. Signals below 660[degrees]C for these UHTCs are attributed to the decomposition of organics present in the boron nitride spray, binder, dispersant, and surfactant. The signals above 900[degrees]C were determined to be CO and CO2

A comparison of systems for measuring methane emissions from sheep

Two experiments were conducted, at ADAS Drayton in the autumn and winter 1996/1997, to compare methane (CH4) emissions from sheep housed either in a polytunnel system or in open-circuit respiration chambers. In each system, the sheep received maintenance levels of either cut grass or high temperature dried grass pellets (HTDG). All experiments in the tunnel were conducted on concrete to avoid any interactions of the CH4 with the soil/plant environment. The results suggested that CH4 production from the open-circuit chambers was greater than from the tunnel system (26·9±0·46 v. 31·7±0·35 l/kg dry matter intake (±S.E.) for open circuit respiration chambers and tunnel, respectively). Recovery tests gave similar results for both systems (95·5–97·9% for tunnels and 89·2–96·7% for chambers), and confirmed that both methods give good quantitative recovery of added CH4, and can therefore be assumed to provide reliable estimates of emissions from animals. There is no technical explanation, therefore, for the different estimates of emissions provided by the two systems. Further studies are required to understand the reasons for the differences and in particular, the possible links between animal behaviour induced by the two systems and CH4 emission rates

Traits associated with brace root characters implicate light and hormonal signaling pathways [abstract]

Abstract only availableMaize brace roots provide the plant with access to water and nutrients in the soil, increase stability, and improve lodging resistance. The goal of this study is to connect brace root traits to traits linked to developmental and hormonal pathways, and light perception by multiple regression and correlation analysis. Two replications of twenty-seven diverse lines of maize were planted and measured for light perception traits, maturity and phase transition traits, in the summer of 2007. Forward selection and backwards elimination multiple regression and correlation analysis were performed in SAS. A significance threshold of 0.05 for entry or elimination was used in the multiple regression analysis. Model R-squared values had a range of 0.47 to 0.64. The variables significant for the number of nodes with brace roots and the number of brace roots at node one were related to the growth hormone gibberellic acid (GA) such as average internode length and juvenile and transition leaf number. Soil node diameter and ear height were also linked to root traits and are under the genetic control of the light response regulators phytochromes B1 and B2. A proposed model showing how GA and light perception affect plant development is reported. This research was funded by the Undergraduate Mentoring in Environmental Biology and The Life Science Mission Enhancement programs.NSF Undergraduate Mentoring in Environmental Biology; The Life Science Mission Enhancement Progra

Modeling the relationship between light perception traits and brace root development in Zea mays L. [abstract]

Abstract only availableMaize (Zea mays L.) brace roots are responsible for physical stability in the soil and for water and nutrient acquisition in maize. The objective of this project is to investigate how traits related to light perception affect brace root development. Previous work has shown that light perception affects total root development and that reduced lighting conditions cause a decline in all root growth, even more drastically than in the rest of the plant (Y. Hébert, E. Guingo, and O. Loudet, 2001). Trait data for 98 diverse lines were collected primarily from 2004 to 2005 for traits related to light perception and maturity. Correlation analysis and multiple regression analysis were performed to produce models that identify traits significantly affecting brace root development and their interactions. Our model shows that in 2005, light perception traits were not as significant as in 2004 indicating that the effect of light perception on brace root number may be environmentally dependent. This could be because the much hotter temperatures in 2005 caused the light perception mechanism to be saturated masking the interaction, whereas in 2004, the temperate environment caused the expression of the light perception and brace root interaction. The experimental model will then be validated using data collected on the identified traits from 25 diverse lines grown in the field

Stochastic Resonance in Nonpotential Systems

We propose a method to analytically show the possibility for the appearance of a maximum in the signal-to-noise ratio in nonpotential systems. We apply our results to the FitzHugh-Nagumo model under a periodic external forcing, showing that the model exhibits stochastic resonance. The procedure that we follow is based on the reduction to a one-dimensional dynamics in the adiabatic limit, and in the topology of the phase space of the systems under study. Its application to other nonpotential systems is also discussed.Comment: Submitted to Phys. Rev.

T-cell number and subtype influence the disease course of primary chronic lymphocytic leukaemia xenografts in alymphoid mice.

Chronic lymphocytic leukaemia (CLL) cells require microenvironmental support for their proliferation. This can be recapitulated in highly immunocompromised hosts in the presence of T cells and other supporting cells. Current primary CLL xenograft models suffer from limited duration of tumour cell engraftment coupled with gradual T-cell outgrowth. Thus, a greater understanding of the interaction between CLL and T cells could improve their utility. In this study, using two distinct mouse xenograft models, we investigated whether xenografts recapitulate CLL biology, including natural environmental interactions with B-cell receptors and T cells, and whether manipulation of autologous T cells can expand the duration of CLL engraftment. We observed that primary CLL xenografts recapitulated both the tumour phenotype and T-cell repertoire observed in patients and that engraftment was significantly shorter for progressive tumours. A reduction in the number of patient T cells that were injected into the mice to 2-5% of the initial number or specific depletion of CD8+ cells extended the limited xenograft duration of progressive cases to that characteristic of indolent disease. We conclude that manipulation of T cells can enhance current CLL xenograft models and thus expand their utility for investigation of tumour biology and pre-clinical drug assessment

Young children's research: children aged 4-8 years finding solutions at home and at school

Children's research capacities have become increasingly recognised by adults, yet children remain excluded from the academy, with reports of their research participation generally located in adults' agenda. Such practice restricts children's freedom to make choices in matters affecting them, underestimates children’s capabilities and denies children particular rights. The present paper reports on one aspect of a small-scale critical ethnographic study adopting a constructivist grounded approach to conceptualise ways in which children's naturalistic behaviours may be perceived as research. The study builds on multi-disciplinary theoretical perspectives, embracing 'new' sociology, psychology, economics, philosophy and early childhood education and care (ECEC). Research questions include: 'What is the nature of ECEC research?' and 'Do children’s enquiries count as research?' Initially, data were collected from the academy: professional researchers (n=14) confirmed 'finding solutions' as a research behaviour and indicated children aged 4-8 years, their practitioners and primary carers as 'theoretical sampling'. Consequently, multi-modal case studies were constructed with children (n=138) and their practitioners (n=17) in three ‘good’ schools, with selected children and their primary carers also participating at home. This paper reports on data emerging from children aged 4-8 years at school (n=17) and at home (n=5). Outcomes indicate that participating children found diverse solutions to diverse problems, some of which they set themselves. Some solutions engaged children in high order thinking, whilst others did not; selecting resources and trialing activities engaged children in 'finding solutions'. Conversely, when children's time, provocations and activities were directed by adults, the quality of their solutions was limited, they focused on pleasing adults and their motivation to propose solutions decreased. In this study, professional researchers recognised 'finding solutions' as research behaviour and children aged 4-8 years naturalistically presented with capacities for finding solutions; however, the children's encounters with adults affected the solutions they found

Walk well:a randomised controlled trial of a walking intervention for adults with intellectual disabilities: study protocol

Background - Walking interventions have been shown to have a positive impact on physical activity (PA) levels, health and wellbeing for adult and older adult populations. There has been very little work carried out to explore the effectiveness of walking interventions for adults with intellectual disabilities. This paper will provide details of the Walk Well intervention, designed for adults with intellectual disabilities, and a randomised controlled trial (RCT) to test its effectiveness. Methods/design - This study will adopt a RCT design, with participants allocated to the walking intervention group or a waiting list control group. The intervention consists of three PA consultations (baseline, six weeks and 12 weeks) and an individualised 12 week walking programme. A range of measures will be completed by participants at baseline, post intervention (three months from baseline) and at follow up (three months post intervention and six months from baseline). All outcome measures will be collected by a researcher who will be blinded to the study groups. The primary outcome will be steps walked per day, measured using accelerometers. Secondary outcome measures will include time spent in PA per day (across various intensity levels), time spent in sedentary behaviour per day, quality of life, self-efficacy and anthropometric measures to monitor weight change. Discussion - Since there are currently no published RCTs of walking interventions for adults with intellectual disabilities, this RCT will examine if a walking intervention can successfully increase PA, health and wellbeing of adults with intellectual disabilities

MICE: The muon ionization cooling experiment. Step I: First measurement of emittance with particle physics detectors

Copyright @ 2011 APSThe Muon Ionization Cooling Experiment (MICE) is a strategic R&D project intended to demonstrate the only practical solution to providing high brilliance beams necessary for a neutrino factory or muon collider. MICE is under development at the Rutherford Appleton Laboratory (RAL) in the United Kingdom. It comprises a dedicated beamline to generate a range of input muon emittances and momenta, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. The emittance of the incoming beam will be measured in the upstream magnetic spectrometer with a scintillating fiber tracker. A cooling cell will then follow, alternating energy loss in Liquid Hydrogen (LH2) absorbers to RF cavity acceleration. A second spectrometer, identical to the first, and a second muon identification system will measure the outgoing emittance. In the 2010 run at RAL the muon beamline and most detectors were fully commissioned and a first measurement of the emittance of the muon beam with particle physics (time-of-flight) detectors was performed. The analysis of these data was recently completed and is discussed in this paper. Future steps for MICE, where beam emittance and emittance reduction (cooling) are to be measured with greater accuracy, are also presented.This work was supported by NSF grant PHY-0842798

Choosing to live with home dialysis-patients' experiences and potential for telemedicine support: a qualitative study

<p>Abstract</p> <p>Background</p> <p>This study examines the patients' need for information and guidance in the selection of dialysis modality, and in establishing and practicing home dialysis. The study focuses on patients' experiences living with home dialysis, how they master the treatment, and their views on how to optimize communication with health services and the potential of telemedicine.</p> <p>Methods</p> <p>We used an inductive research strategy and conducted semi-structured interviews with eleven patients established in home dialysis. Our focus was the patients' experiences with home dialysis, and our theoretical reference was patients' empowerment through telemedicine solutions. Three informants had home haemodialysis (HHD); eight had peritoneal dialysis (PD), of which three had automated peritoneal dialysis (APD); and five had continuous ambulatory peritoneal dialysis (CAPD). The material comprises all PD-patients in the catchment area capable of being interviewed, and all known HHD-users in Norway at that time.</p> <p>Results</p> <p>All of the interviewees were satisfied with their choice of home dialysis, and many experienced a normalization of daily life, less dominated by disease. They exhibited considerable self-management skills and did not perceive themselves as ill, but still required very close contact with the hospital staff for communication and follow-up. When choosing a dialysis modality, other patients' experiences were often more influential than advice from specialists. Information concerning the possibility of having HHD, including knowledge of how to access it, was not easily available. Especially those with dialysis machines, both APD and HHD, saw a potential for telemedicine solutions.</p> <p>Conclusions</p> <p>As home dialysis may contribute to a normalization of life less dominated by disease, the treatment should be organized so that the potential for home dialysis can be fully exploited. Pre-dialysis information should be unbiased and include access to other patients' experiences. Telemedicine may potentially facilitate a communication-based follow-up and improve safety within the home setting, making it easier to choose and live with home dialysis.</p