1,493 research outputs found

    Balancing teaching and research in higher education

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    Lepton-Flavour Violation in Ordinary and Supersymmetric Grand Unified Theories

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    By an explicit calculation we show that in ordinary SU(5) logarithmic divergence in the amplitude of Ό→eÎł\mu \to e\gamma cancels among diagrams and remaining finite part is suppressed by at least 1/MGUT21/M_{GUT}^2. In SUSY SU(5), when the effect of flavour changing wave function renormalization is taken into account such logarithmic correction disappears, provided a condition is met among SUSY breaking masses. In SUGRA-inspired SUSY GUT the remaining logarithmic effect is argued not to be taken as a prediction of the theory.Comment: 8 pages, LaTeX209 file, using axodraw.st

    Exploration of Possible Quantum Gravity Effects with Neutrinos II: Lorentz Violation in Neutrino Propagation

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    It has been suggested that the interactions of energetic particles with the foamy structure of space-time thought to be generated by quantum-gravitational (QG) effects might violate Lorentz invariance, so that they do not propagate at a universal speed of light. We consider the limits that may be set on a linear or quadratic violation of Lorentz invariance in the propagation of energetic neutrinos, v/c=[1 +- (E/M_\nuQG1)] or [1 +- (E/M_\nu QG2}^2], using data from supernova explosions and the OPERA long-baseline neutrino experiment.Comment: 8 pages, 6 figures, proceedings for invited talk by A.Sakharov at DISCRETE'08, Valencia, Spain; December 200

    Supernova Neutrino Oscillations

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    Observing a high-statistics neutrino signal from a galactic supernova (SN) would allow one to test the standard delayed explosion scenario and may allow one to distinguish between the normal and inverted neutrino mass ordering due to the effects of flavor oscillations in the SN envelope. One may even observe a signature of SN shock-wave propagation in the detailed time-evolution of the neutrino spectra. A clear identification of flavor oscillation effects in a water Cherenkov detector probably requires a megatonne-class experiment.Comment: Proc. 129 Nobel Symposium "Neutrino Physics", 19-24 Aug 2004, Swede

    Dynamics of a map with power-law tail

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    We analyze a one-dimensional piecewise continuous discrete model proposed originally in studies on population ecology. The map is composed of a linear part and a power-law decreasing piece, and has three parameters. The system presents both regular and chaotic behavior. We study numerically and, in part, analytically different bifurcation structures. Particularly interesting is the description of the abrupt transition order-to-chaos mediated by an attractor made of an infinite number of limit cycles with only a finite number of different periods. It is shown that the power-law piece in the map is at the origin of this type of bifurcation. The system exhibits interior crises and crisis-induced intermittency.Comment: 28 pages, 17 figure

    Multiform antimicrobial resistance from a metabolic mutation

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    A critical challenge for microbiology and medicine is how to cure infections by bacteria that survive antibiotic treatment by persistence or tolerance. Seeking mechanisms behind such high survival, we developed a forward-genetic method for efficient isolation of high24 survival mutants in any culturable bacterial species. We found that perturbation of an essential biosynthetic pathway (arginine biosynthesis) in a mycobacterium generated three distinct forms of resistance to diverse antibiotics, each mediated by induction of WhiB7— high persistence and tolerance to kanamycin, high survival upon exposure to rifampicin, and MIC-shifted resistance to clarithromycin. As little as one base change in a gene encoding a metabolic pathway component conferred multiple forms of resistance to multiple antibiotics with different targets. This extraordinary resilience may help explain how sub31 sterilizing exposure to one antibiotic in a regimen can induce resistance to others and invites development of drugs targeting the mediator of multiform resistance, WhiB7

    PineappleDB: An online pineapple bioinformatics resource

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    BACKGROUND: A world first pineapple EST sequencing program has been undertaken to investigate genes expressed during non-climacteric fruit ripening and the nematode-plant interaction during root infection. Very little is known of how non-climacteric fruit ripening is controlled or of the molecular basis of the nematode-plant interaction. PineappleDB was developed to provide the research community with access to a curated bioinformatics resource housing the fruit, root and nematode infected gall expressed sequences. DESCRIPTION: PineappleDB is an online, curated database providing integrated access to annotated expressed sequence tag (EST) data for cDNA clones isolated from pineapple fruit, root, and nematode infected root gall vascular cylinder tissues. The database currently houses over 5600 EST sequences, 3383 contig consensus sequences, and associated bioinformatic data including splice variants, Arabidopsis homologues, both MIPS based and Gene Ontology functional classifications, and clone distributions. The online resource can be searched by text or by BLAST sequence homology. The data outputs provide comprehensive sequence, bioinformatic and functional classification information. CONCLUSION: The online pineapple bioinformatic resource provides the research community with access to pineapple fruit and root/gall sequence and bioinformatic data in a user-friendly format. The search tools enable efficient data mining and present a wide spectrum of bioinformatic and functional classification information. PineappleDB will be of broad appeal to researchers investigating pineapple genetics, non-climacteric fruit ripening, root-knot nematode infection, crassulacean acid metabolism and alternative RNA splicing in plants

    Use of piggery effluent for point-of-management diagnostics: A proof of concept

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    During the COVID-19 pandemic, detection of the virus in sewage water was used to determine disease spread in the community. Piggery effluent or waste is composed of faeces, urine, oronasal secretions, feed residues and other miscellaneous components which are diluted in water and released into the environment (Rate, 1997). This blended composition of effluent, along with evidence that several pathogenic bacteria have already been isolated from effluent (Chinivasagam et al., 2004) suggest that it could be useful to monitor pathogen prevalence in a herd at a given point in time. This monitoring could help in early detection and improved control of disease outbreaks that could potentially cause significant economic losses and decreased animal welfare. This point-of-management (POM) approach and better control of infectious diseases would also reduce the need for antimicrobials, improving the sustainability of intensive pig production and reducing the risk of antimicrobial resistance genes entering the food chain or the environment. The nucleic acid amplification-based assay known as Loop-mediated isothermal amplification (LAMP) has been widely adopted for POM diagnostics due to its high sensitivity, accuracy, affordability and quick turnaround time. Therefore, this study was designed to produce a proof-of-concept effluent testing methodology through LAMP-based POM assay, to determine if this tool is useful to monitor pathogens at the shed or herd level. Due to the composition of effluent and the ease of implementation and low cost of LAMP assays, it was hypothesised that LAMP assays could be used to detect a common pathogen in pig effluent for the purpose of POM diagnostics

    Re-Examination of Generation of Baryon and Lepton Number Asymmetries by Heavy Particle Decay

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    It is shown that wave function renormalization can introduce an important contribution to the generation of baryon and lepton number asymmetries by heavy particle decay. These terms, omitted in previous analyses, are of the same order of magnitude as the standard terms. A complete cancellation of leading terms can result in some interesting cases.Comment: 12 pages, 2 Feynman graphs (not included), UPR-055
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