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Search Results: 1 - 10 of 327744 matches for " E. de;Irvine "
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Characterisation of conductivity of the (Ce xY0.2-x)Sc0.6 Zr3.2O8-δ (0 < x < 0.2) system and composition Ce0.04Y0.02Sc0.67Zr3.27O 7.66 as function of time
Carvalho, E. de;Irvine, J. T. S.;
Ceramica , 2012, DOI: 10.1590/S0366-69132012000100002
Abstract: the conductivity behaviour of the (cexy0.2-x)sc0.6 zr3.2o8-δ (0 < x < 0.2) system and composition ce0.04y0.02sc0.67zr3.27o 7.66 have been investigated as function of time using impedance spectroscopy. all samples were prepared by sol-gel and combustion process, sintered at 1500 °c for 12 h and the densities obtained were between 92 and 97%. the electrical measurements were performed at 600 °c. the conductivity values were fairly stable during the first 1800 h of the experiment but after this time the conductivity decreases. for some compositions of the system a semi-circle is detected through time, with capacitance values of an order of magnitude lower, 10-8 f/cm. this semi-circle becomes well defined with time. after the experiment, sem pictures show that grain boundary is well defined and an increase of pore inside grains, in some cases the surface is damaged showing cracks and fissures indicating microstructure deterioration.
Lithographically and electrically controlled strain effects on anisotropic magnetoresistance in (Ga,Mn)As
E. De Ranieri,A. W. Rushforth,K. Vyborny,U. Rana,E. Ahmed,R. P. Campion,C. T. Foxon,B. L. Gallagher,A. C. Irvine,J. Wunderlich,T. Jungwirth
Physics , 2008, DOI: 10.1088/1367-2630/10/6/065003
Abstract: It has been demonstrated that magnetocrystalline anisotropies in (Ga,Mn)As are sensitive to lattice strains as small as 10^-4 and that strain can be controlled by lattice parameter engineering during growth, through post growth lithography, and electrically by bonding the (Ga,Mn)As sample to a piezoelectric transducer. In this work we show that analogous effects are observed in crystalline components of the anisotropic magnetoresistance (AMR). Lithographically or electrically induced strain variations can produce crystalline AMR components which are larger than the crystalline AMR and a significant fraction of the total AMR of the unprocessed (Ga,Mn)As material. In these experiments we also observe new higher order terms in the phenomenological AMR expressions and find that strain variation effects can play important role in the micromagnetic and magnetotransport characteristics of (Ga,Mn)As lateral nanoconstrictions.
Schubert Calculus and Threshold Polynomials of Affine Fusion
S. E. Irvine,M. A. Walton
Mathematics , 2000, DOI: 10.1016/S0550-3213(00)00404-1
Abstract: We show how the threshold level of affine fusion, the fusion of Wess-Zumino-Witten (WZW) conformal field theories, fits into the Schubert calculus introduced by Gepner. The Pieri rule can be modified in a simple way to include the threshold level, so that calculations may be done for all (non-negative integer) levels at once. With the usual Giambelli formula, the modified Pieri formula deforms the tensor product coefficients (and the fusion coefficients) into what we call threshold polynomials. We compare them with the q-deformed tensor product coefficients and fusion coefficients that are related to q-deformed weight multiplicities. We also discuss the meaning of the threshold level in the context of paths on graphs.
Magnetocrystalline anisotropy controlled local magnetic configurations in (Ga,Mn)As spin-transfer-torque microdevices
J. Wunderlich,A. C. Irvine,J. Zemen,V. Holy,A. W. Rushforth,E. De Ranieri,U. Rana,K. Vyborny,Jairo Sinova,C. T. Foxon,R. P. Campion,D. A. Williams,B. L. Gallagher,T. Jungwirth
Physics , 2007,
Abstract: The large saturation magnetization in conventional dense moment ferromagnets offers flexible means of manipulating the ordered state through demagnetizing shape anisotropy fields but these dipolar fields, in turn, limit the integrability of magnetic elements in information storage devices. We show that in a (Ga,Mn)As dilute moment ferromagnet, with comparatively weaker magnetic dipole interactions, locally tunable magnetocrystalline anisotropy can take the role of the internal field which determines the magnetic configuration. Experiments and theoretical modeling are presented for lithographically patterned microchannels and the phenomenon is attributed to lattice relaxations across the channels. The utility of locally controlled magnetic anisotropies is demonstrated in current induced switching experiments. We report structure sensitive, current induced in-plane magnetization switchings well below the Curie temperature at critical current densities 10^5 Acm^-2. The observed phenomenology shows signatures of a contribution from domain-wall spin-transfer-torque effects.
Current-driven domain wall motion across a wide temperature range in a (Ga,Mn)(As,P) device
K. Y. Wang,K. W. Edmonds,A. C. Irvine,G. Tatara,E. De Ranieri,J. Wunderlich,K. Olejnik,A. W. Rushforth,R. P. Campion,D. A. Williams,C. T. Foxon,B. L. Gallagher
Physics , 2010, DOI: 10.1063/1.3532095
Abstract: Current-driven magnetic domain wall motion is demonstrated in the quaternary ferromagnetic semiconductor (Ga,Mn)(As,P) at temperatures well below the ferromagnetic transition temperature, with critical currents of the order 10^5Acm^-2. This is enabled by a much weaker domain wall pinning compared to (Ga,Mn)As layers grown on a strain-relaxed buffer layer. The critical current is shown to be comparable with theoretical predictions. The wide temperature range over which domain wall motion can be achieved indicates that this is a promising system for developing an improved understanding of spin-transfer torque in systems with strong spin-orbit interaction.
Energy from Waste: Reuse of Compost Heat as a Source of Renewable Energy
G. Irvine,E. R. Lamont,B. Antizar-Ladislao
International Journal of Chemical Engineering , 2010, DOI: 10.1155/2010/627930
Abstract: An in-vessel tunnel composting facility in Scotland was used to investigate the potential for collection and reuse of compost heat as a source of renewable energy. The amount of energy offered by the compost was calculated and seasonal variations analysed. A heat exchanger was designed in order to collect and transfer the heat. This allowed heated water of C to be obtained. The temperature could be further increased to above C by passing it through multiple tunnels in series. Estimated costs for installing and running the system were calculated. In order to analyse these costs alternative solar thermal and ground source heat pump systems were also designed. The levels of supply and economic performance were then compared. A capital cost of 11,662 and operating cost of 1,039 per year were estimated, resulting in a cost of 0.50 per kWh for domestic water and 0.10 per kWh for spatial heat. Using the heat of the compost was found to provide the most reliable level of supply at a similar price to its rivals. 1. Introduction Composting is an aerobic process where organic materials are biologically decomposed, producing mainly compost, carbon dioxide, water, and heat. Conventional composting processes typically comprise four major microbiological stages in relation to temperature: mesophilic, thermophilic, cooling, and maturation, during which the structure of the microbial community also changes, and the final product is compost [1]. In recent years, the development and widespread use of more expensive in-vessel systems for the processing of biowastes has resulted from legislative pressures on the safety of the composting process and the subsequent use of the compost product [2]. Such systems allow for much more precise control of the composting process particularly in terms of moisture and temperature control [3]. Thus, current composting approaches and technologies tend to emphasize the use of high temperatures ( 7 ) in order to meet regulatory requirements for pathogen control [2]. Compost has been widely used as soil conditioners and soil fertilizers. This practice is recommended, as soil fertility needs more than ever to be sustained. Food demand is increasing rapidly in non-OECD (Organisation for Economic Co-operation and Development) countries, and it is in those countries particularly where organic waste needs to be diverted from landfill sites to composting practices, so compost can enhance soil fertility [4]. In OECD countries, where composting of organic waste is already established, its use as a landfill cover to abate greenhouse gas emissions has
Spontaneous Symmetry Breaking for Scalar QED with Non-minimal Chern-Simons Coupling
D. S. Irvine,M. E. Carrington,G. Kunstatter,D. Pickering
Physics , 2001, DOI: 10.1103/PhysRevD.64.045015
Abstract: We investigate the two-loop effective potential for both minimally and non-minimally coupled Maxwell-Chern-Simons theories. The non-minimal gauge interaction represents the magnetic moment interaction between a charged scalar and the electromagnetic field. In a previous paper we have shown that the two loop effective potential for this model is renormalizable with an appropriate choice of the non-minimal coupling constant. We carry out a detailed analysis of the spontaneous symmetry breaking induced by radiative corrections. As long as the renormalization point for all couplings is chosen to be the true minimum of the effective potential, both models predict the presence of spontaneous symmetry breaking. Two loop corrections are small compared to the one loop result, and thus the symmetry breaking is perturbatively stable.
Evaluation of Sensory Properties of Probiotic Yogurt Containing Food Products with Prebiotic Fibresin Mwanza, Tanzania  [PDF]
Stephanie L. Irvine, Sharareh Hekmat
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.25061
Abstract: Yogurt becomes a functional food upon incorporating probiotics-live microorganisms which when adequately administered confer health benefits. Prebiotics are fermentable fibres that nourish beneficial gastrointestinal microflora enhance the functionality of probiotics. This research aimed to improve the acceptability and functionality of probiotic yogurt produced in Mwanza, Tanzania by incorporating probiotic food ingredients. The probiotic culture Lactobacillus rhamnosus GR-1 and standard yogurt cultures Lactobacillus delbrueckii bulgaricus and Steptococcus thermophilus were used to manufacture yogurt, then locally available prebiotic food ingredients containing fructooligosaccha- ride/inulin were incorporated. A nine-point facial hedonic scale was used to evaluate five yogurt samples. A mean score between one and three indicated that the sample product was well accepted. Probiotic yogurt containing onions, garlic and sweet potato received a score of 1.6 ± 0.84 (p < 0.01); banana and honey was 2.5 ± 1.72 (p = 0.02); and leafy greens, onions and garlic was 2.6 ± 1.54 (p = 0.04). Samples containing beans, 4.4 ± 1.99 (p > 0.90), and plantains, 5.3 ± 2.56 (p > 0.90) were not well accepted. Sweet, mildly flavored prebiotic ingredients were most successfully incorpo- rated into probiotic yogurt in Mwanza.
Evergreen Brick Works: An Innovation and Sustainability Case Study
Seana Irvine
Technology Innovation Management Review , 2012,
Abstract: Technology is rapidly being deployed to advance social innovation that creates lasting change. This case study of Evergreen Brick Works explores how Evergreen is leveraging the power of its unique new campus as a showcase for advancing sustainability-related behavioural change along with new and emerging state-of-the-art technologies to advance its mission. The ultimate success of these technologies will be in their ability to engage larger numbers and greater diversity among participants, and in their ability to translate new insights into on-the-ground change in their communities. The article also identifies that the need for an organizational network mindset is as important as the technologies to achieve these changes.
Antigen-Displaying Lipid-Enveloped PLGA Nanoparticles as Delivery Agents for a Plasmodium vivax Malaria Vaccine
James J. Moon, Heikyung Suh, Mark E. Polhemus, Christian F. Ockenhouse, Anjali Yadava, Darrell J. Irvine
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0031472
Abstract: The parasite Plasmodium vivax is the most frequent cause of malaria outside of sub-Saharan Africa, but efforts to develop viable vaccines against P. vivax so far have been inadequate. We recently developed pathogen-mimicking polymeric vaccine nanoparticles composed of the FDA-approved biodegradable polymer poly(lactide-co-glycolide) acid (PLGA) “enveloped” by a lipid membrane. In this study, we sought to determine whether this vaccine delivery platform could be applied to enhance the immune response against P. vivax sporozoites. A candidate malaria antigen, VMP001, was conjugated to the lipid membrane of the particles, and an immunostimulatory molecule, monophosphoryl lipid A (MPLA), was incorporated into the lipid membranes, creating pathogen-mimicking nanoparticle vaccines (VMP001-NPs). Vaccination with VMP001-NPs promoted germinal center formation and elicited durable antigen-specific antibodies with significantly higher titers and more balanced Th1/Th2 responses in vivo, compared with vaccines composed of soluble protein mixed with MPLA. Antibodies raised by NP vaccinations also exhibited enhanced avidity and affinity toward the domains within the circumsporozoite protein implicated in protection and were able to agglutinate live P. vivax sporozoites. These results demonstrate that these VMP001-NPs are promising vaccines candidates that may elicit protective immunity against P. vivax sporozoites.
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