349,898 research outputs found
Positronium Decay into a Photon and Neutrinos
No full textWe determine the rates, photon energy and angular distributions of positronium decays into a photon and a neutrino-antineutrino pair, . We find that both positronium spin states have access to this decay channel, contrary to a previously published result. The low-energy tails of the spectra are shown to be sensitive to binding effects in positronium and agree with Low's theorem. Additionally, we find a connection between the behaviour of the soft photon spectrum in both and decays, and the Stark effect
The influence of TiO<sub>2</sub> nanoparticle incorporation on surface potential decay of corona-resistant polyimide nanocomposite films
No full textPI nanocomposite films containing surface modified nanoparticles by employing silane coupling agent were prepared using in-situ dispersion polymerization process. The surface potential decay measurements on films were investigated over the different negative corona-charged voltages and times in a controlled environment where temperature and relative humidity were kept at 21 ºC and 45%, respectively. There is a significant change in the surface potential decay characteristics after nano-fillers were introduced into polyimide. The surface potential decay pattern depends also on the amount of nano-fillers. The possible surface potential decay and corona resistance mechanisms responsible for the observed phenomena were discussed
Incorporating Lindblad Decay Dynamics into Mixed Quantum-Classical Simulations
No full textWe derive the L-MFE method to incorporate Lindblad jump operator dynamics into the mean-field Ehrenfest (MFE) approach. We map the density matrix evolution of Lindblad dynamics onto pure state coefficients using trajectory averages. We use simple assumptions to construct the L-MFE method that satisfies this exact mapping. This establishes a method that exactly reproduces Lindblad decay dynamics using a wavefunction description, with deterministic changes of the magnitudes of the quantum expansion coefficients, while only adding on a stochastic phase. We further demonstrate that when including nuclei in the Ehrenfest dynamics, the L-MFE method gives semi-quantitatively accurate results, with the accuracy limited by the accuracy of the approximations present in the semiclassical MFE approach. This work provides a general framework to incorporate Lindblad dynamics into semiclassical or mixed quantum-classical simulations
Beckett and Decay
No full textThe word 'decay' is often used by critics in general reference to Beckett's thematic emphasis and philosophical outlook. However, this book explores the idea of decay as the fundamental core of Beckett's work, dominating it thematically, linguistically and artistically. Kathryn White explores Beckett's representation of physical decay, mental and spiritual deterioration and finally the idea that 'decay' is to be found in language itself. This study explores the importance of both theme and form in Beckett's work and considers whether Beckett will, in future generations, be remembered both for his representation of existence and his innovations in language.Intro -- Contents -- Acknowledgements -- Introduction -- Part I: Physical Decay -- 1. The Body Infirm -- 2. Old Age: The Dictatorship of Time -- 3. The Decaying Landscape -- 4. Moribund Man: Beckett and Death -- Part II: Mental Decline and Spiritual Attrition -- 5. The Trap of Memory -- 6. Tired Minds -- 7. Perceptions of Insanity -- 8. 'I Can't Go On, I'll Go On': The Ebbing Spirit -- Part III: Death of the Word -- 9. Minimalism and Reductionism: Advancing Towards Lessness -- 10. Dramaticules -- 11. The Miniaturist of the Word: The Shorter Prose -- 12. Voices, Ghosts, Silence: Into Nothingness -- Conclusion -- Notes -- Bibliography -- Index -- A -- B -- C -- D -- E -- F -- G -- H -- I -- J -- K -- L -- M -- P -- S -- T -- U -- V -- W -- YThe word 'decay' is often used by critics in general reference to Beckett's thematic emphasis and philosophical outlook. However, this book explores the idea of decay as the fundamental core of Beckett's work, dominating it thematically, linguistically and artistically. Kathryn White explores Beckett's representation of physical decay, mental and spiritual deterioration and finally the idea that 'decay' is to be found in language itself. This study explores the importance of both theme and form in Beckett's work and considers whether Beckett will, in future generations, be remembered both for his representation of existence and his innovations in language.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
Submission to Commission of Inquiry into Newfoundland Transportation
No full textSubmission to Commission of Inquiry into Newfoundland Transportation, August 1, 1977Handwritten notes in margin
Decay Fungi from New Zealand Leaky Buildings: Isolation, Identification and Preservative Resistance
No full textLeaky buildings are those that show elevated moisture contents of the framing timber, which can subsequently lead to the establishment of fungal and bacterial decay. Prior to this study, the causative agents of the decay in these leaky buildings were unknown, though it was suspected to be one or more species of decay fungi. Therefore, the overall goal of this multi-disciplinary PhD thesis research was to determine the causative agents of decay in leaky buildings of New Zealand in an effort to develop solutions for both their remediation and future prevention.
Use of molecular biology methodology and classical mycological techniques based on morphology enabled identification of decay fungi from framing timber and air samples of leaky New Zealand buildings and provided insight into relative importance based on isolation frequency. In most cases, fungi colonising Pinus radiata D. Don were isolated to produce pure cultures. Mycelia from these cultures on agar media were collected to extract DNA. To identify the fungi to the species level, polymerase chain reaction (PCR) with fungal specific DNA primer pairs were performed followed by DNA sequencing of the internal transcribed spacer (ITS) region. Identification was by BLAST (Basic Local Alignment Search Tool) search on sequences in known GenBanks. In total, 421 samples from leaky buildings were processed, predominately untreated P. radiata decayed framing timber and also fibre cement boards and building paper. From these, sixty-eight fungal identifications were made. The only taxa that were isolated with significant frequency were identified as 4 basidiomycete species, as follows, along with the number of times they were isolated from the 421 samples:
• Gloeophyllum sepiarium (Wulf.: Fr.) Karst. 13x
• Oligoporus placenta (Fries 1865) Gilb. In Ryv.1985 11x
• Antrodia sinuosa (Fr.) Karst. 8x
• Gloeophyllum trabeum (Fr.) Murr. 4x
Although these species were identified repeatedly, in total they represent less than 10% of the total samples and, therefore, it is concluded that the leaky building decay samples represent high fungal biodiversity.
An aerial spore study of internal air, wall cavity air and exterior air of leaky buildings was carried out using a Merck MAS-100 instrument which collects spores directly onto selective media plates. Viable fungal aerial spores were detected at every sampling location tested at the leaky buildings, by the criteria of culturing, with a highest mean of 3714 colony-forming units (CFU) per cubic metre found in the cavities of water-damaged walls. This aerial spore study in conjunction with isolation from decayed wood samples from the same leaky buildings enabled identification of G. sepiarium and A. sinuosa at the same test site. The use of carboxymethylcellulose medium further demonstrated the presence of potential cellulose-degrading fungi within and around the location. Overall, the combination of direct sampling of timber and air sampling proved useful for detection of fungal species variability at a multi-unit building.
Four decay fungi isolated from New Zealand leaky buildings and two standard control decay fungi (Coniophora puteana and Serpula lacrymans) were submitted to laboratory wood block testing to determine the effectiveness of currently used wood framing preservatives under laboratory conditions before and after a standard leaching regime. P. radiata blocks were treated with water based boron copper azole and solvent based IPBC propiconazole plus tebuconazole (1:1) preservatives and exposed to the basidiomycetes for 12 weeks. Mass loss for the fungal decay-infected samples was recorded of up to 55% for preservative-treated samples, up to 62% mass loss for leached samples and up to 58% mass loss for un-preservative treated samples. Additionally, well defined dosage responses and approximate toxic thresholds were obtained for all preservatives tested. Results suggested that the minimum IPBC retention specified by Hazard Class 1.2 of NZS3640:2003 (0.025% m/m) is on the low side, and demonstrated after the 2 week leaching regime complete loss of efficacy of boron at 0.4% m/m boric acid equivalent (BAE).
This PhD research gave a first overview of fungi occurring in New Zealand leaky buildings, and it demonstrated the following key aspects of wood preservation:
1. The isolated test fungus Antrodia sinuosa was more difficult to control with propiconazole plus tebuconazole at retention 0.007% m/m than the known tolerant fungus Oligoporus placenta;
2. Boron at Hazard Class 1.2 retention of 0.4% m/m BAE was not toxic to Oligoporus placenta;
3. Serpula lacrymans exhibited tolerance to the highest retention of 0.06 %m/m tebuconazole plus propiconazole; and
4. Gloeophyllum species appeared susceptible to all wood preservatives.
In order to correlate fungal colonisation and wood decay, colonised wood blocks were studied using light microscopy (LM) and field- emission scanning electron microscopy (FE-SEM). Microscopic observations of P. radiata wood blocks following a standard wood decay test of twelve weeks of fungal colonisation by Serpula lacrymans, Antrodia sinuosa, Oligoporus placenta and Gloeophyllum sepiarium revealed that the two microscopic techniques employed were complementary by allowing features such as pit membranes, chlamydospores or S3/S2 compound middle lamella interface to be photographed in greater detail, allowing for more precise analyses and interpretation of key findings, as follows:
1. Brown rot fungi directly target their apical growth towards degraded pit apetures;
2. Reliance on light microscopy and observed birefringence as a tool to record changes in cell wall crystallinity associated with brown rot decay alone could be misleading;
3. Presence of fine (≤ 1 m) to wide (≥ 3.5 m) bore-hole and hyphal size ranges, and nearly unchanged cell wall thickness of all wood/test fungal combinations, confirmed active decay at moderate to late stages;
4. Some ray parenchyma cells for Antrodia sinuosa, Oligoporus placenta and Gloeophyllum sepiarium colonised blocks were intact throughout late stages of decay, outlining that they were not preferentially degraded early in the brown rot decay process, and
5. Presence of bore-holes, clamp and medallion clamp formation and resting spores (chlamydospores and arthrospores) are fungal specific, can aid in their differentiation and identification, and should be recorded during wood decay studies, as especially resting spores are an important factor when planning remediation strategies.
In summary, this PhD thesis research provided the first comprehensive investigation into the biodiversity of fungi from leaky New Zealand buildings, identified the dominant species and presented details about their micromorphology and their decay patterns. It also demonstrated substantial differences in efficacy of preservative formulations currently (December 2008) approved for framing treatments in New Zealand and possible deficiencies where framing may be subjected to severe leaching. This study also provided the first comparative analyses of viable fungal aerial spores between leaky wall cavities and the surrounding air environment. Subsequently, this research added to the knowledge of the decay fungal species diversity in and around New Zealand leaky buildings, outlined their capabilities to degrade treated and un-treated P. radiata framing timber and illustrated the efficacy of New Zealand approved wood preservatives for their potential as remedial treatment and future prevention
Post-transcriptional regulation of 5-lipoxygenase mRNA expression via alternative splicing and nonsense-mediated mRNA decay
No full text5-Lipoxygenase (5-LO) catalyzes the two initial steps in the biosynthesis of leukotrienes (LT), a group of inflammatory lipid mediators derived from arachidonic acid. Here, we investigated the regulation of 5-LO mRNA expression by alternative splicing and nonsense-mediated mRNA decay (NMD). In the present study, we report the identification of 2 truncated transcripts and 4 novel 5-LO splice variants containing premature termination codons (PTC). The characterization of one of the splice variants, 5-LOΔ3, revealed that it is a target for NMD since knockdown of the NMD factors UPF1, UPF2 and UPF3b in the human monocytic cell line Mono Mac 6 (MM6) altered the expression of 5-LOΔ3 mRNA up to 2-fold in a cell differentiation-dependent manner suggesting that cell differentiation alters the composition or function of the NMD complex. In contrast, the mature 5-LO mRNA transcript was not affected by UPF knockdown. Thus, the data suggest that the coupling of alternative splicing and NMD is involved in the regulation of 5-LO gene expression
A New approach to inclusive decay spectra.
No full textThe main obstacle in describing inclusive decay spectra in QCD — which, in particular, limits
the precision in extrapolating the measured ¯B −→ Xs
rate to the full phase space as well as
in extracting |Vub| from inclusive measurements of charmless semileptonic decays — is their
sensitivity to the non-perturbative momentum distribution of the heavy quark in the meson.
We show that, despite this sensitivity, resummed perturbation theory has high predictive
power. Conventional Sudakov–resummed perturbation theory describing the decay of an onshell
heavy quark yields a divergent expansion. Detailed understanding of this divergence
in terms of infrared renormalons has paved the way for making quantitative predictions. In
particular, the leading renormalon ambiguity cancels out between the Sudakov factor and
the quark pole mass. This cancellation requires renormalon resummation but involves no
non-perturbative information. Additional effects due to the Fermi motion of the quark in
the meson can be systematically taken into account through power corrections, which are only
important near the physical endpoint. This way the moments of the ¯B −→ Xs
spectrum with
experimentally–accessible cuts — which had been so far just parametrized — were recently
computed by perturbative means. At Moriond these predictions were confronted with new
data from BaBar
Wake Evolution of Wing-Body Configuration from Roll-Up to Vortex Decay
No full textThe development of aircraft’s wake vortex from the roll-up until vortex decay is studied. An aircraft model and the surrounding flow field obtained from high-fidelity Reynolds-averaged Navier-Stokes simulation are swept through a ground-fixed computational domain to initialize the wake. After the wake initialization, the large-eddy simulation of the vortical wake is performed until vortex decay. The methodology is tested with the NACA0012 wing and applied to the DLR-F6 wing-body model. The roll-up process of the vorticity sheet from a main wing and the merge of an inboard wing vortex into the wingtip vortex are simulated. Vortex parameters such as the radially averaged circulation, vortex core radius
and vortex separation are also evaluated. The growth rate of the vortex core radius is relatively small during the roll-up where the fine mesh resolution in the LES is required to capture the tiny vortex core in the RANS simulation
Aircraft Wake Vortex Decay in Ground Proximity : Physical Mechanisms and Artificial Enhancement
No full textAircraft wake vortex evolution in ground proximity is investigated numerically with large eddy simulations (LES). The simulations are performed with different modifications of the ground surface in order to trigger rapid vortex decay or to simulate the landing of an aircraft. The impact of environmental turbulence in terms of turbulent winds is taken into account, where wall-resolved and wall-modeled LES are performed for low and high Reynolds number cases, respectively. In order to understand wake
vortex decay mechanisms in ground proximity the interaction of primary and secondary vortices is thoroughly investigated. The results show that vortex decay is initiated and accelerated with obstacles at the ground. In order to optimize obstacle shape and size we show that we can achieve a similar effect with relatively small plates as with large block-shaped barriers. Concerning large Reynolds numbers we show that turbulence effects triggered by the ground can not be modeled by a simple wall model. As a
first approximation of landing we use a ramp at the ground and show that the flow disturbances are similar to the result of flat ground with obstacles. In particular two kinds of so-called end effects are superposed: pressure waves in the vortex core and the propagation of the secondary vortex structures
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