280 research outputs found

    Rainbow Spacetime from a Nonlocal Gravitational Uncertainty Principle

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    Occurrence of spacetime singularities is one of the peculiar features of Einstein gravity, signalling limitation on probing short distances in spacetime. This alludes to the existence of a fundamental length scale in nature. On contrary, Heisenberg quantum uncertainty relation seems to allow for probing arbitrarily small length scales. To reconcile these two conflicting ideas in line with a well known framework of quantum gravity, several modifications of Heisenberg algebra have been proposed. However, it has been extensively argued that such a minimum length would introduce nonlocality in theories of quantum gravity. In this Letter, we analyze a previously proposed deformation of the Heisenberg algebra (i.e. pp(1+λp1)p \rightarrow p (1 + \lambda p^{-1})) for a particle confined in a box subjected to a gravitational field. For the problem in hand, such deformation seems to yield an energy-dependent behavior of spacetime in a way consistent with gravity's rainbow, hence demonstrating a connection between non-locality and gravity's rainbow.Comment: 5 pages, revtex4, 2 figures, to appear in EPL (Europhysics Letters

    Buffalo Genome Projects: Current Situation and Future Perspective in Improving Breeding Programs

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    Buffaloes are farm animals that contribute to food security by providing high quality meat and milk. They can better tolerate the adverse effects of global climate change on their meat and milk production. Despite their advantages, buffaloes are heavily neglected animals with fewer studies compared to other farm animals, hence, the real potential of buffaloes has never been realized. The complete genome sequencing projects of buffaloes are essential to better understanding the buffalos biology and production since they allow scientists to identify important genes and understand how the gene networks interact to determine the critical features of buffaloes. The genome projects are also valuable for gaining better knowledge of growth, development, maintenance, and determining factors associated with increased meat and milk production. Furthermore, having access to a complete genome of high quality and comprehensive annotations provides a powerful tool in breeding programs. The current review surveyed the publicly available buffalo genome projects and studied the impact of incorporating genomic selection into the buffalo breeding program. Our survey of the publicly available buffalo genome projects showed the promise of genomic selection in developing water buffalo science and technology for food security on a global scale.Comment: two figure

    Molecular characterization of two AP2/ERF transcription factor genes from Egyptian tomato cultivar (Edkawy)

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    The tomato is ranked first amongst vegetable crops in Egypt in relation to surface area and production. The Egyptian tomato cultivar Edkawy has shown abiotic stress tolerance characteristics. However, there is not much information about the molecular characterization of this cultivar. Furthermore, information regarding the identification of abiotic stress tolerance genes from the Edkawy tomato cultivar is lacking. Here, we investigated the ability of the Edkawy cultivar to tolerate drought stress. Two varieties were used as a control in this study; Peto86 (sensitive variety) and Strain B (tolerant variety). Edkawy, Peto86 and Strain B varieties were exposed to drought stress by reducing the water supply gradually. Interestingly, Edkawy demonstrated a remarkable tolerance phenotype to drought stress. Furthermore, we identified and isolated two members of the AP2/ERF transcription factor family from Edkawy which are associated with abiotic stress, particularly drought, i.e. ERF1 and ERF5. Protein prediction, validation and active site prediction of ERF1 and ERF5 were also determined. In addition to the domain obtained by the pfam online tool, the interaction between Edkawy ERFs proteins and other proteins in the Solanaceae family was obtained. Furthermore, subcellular localization was determined by the ngLOC and Plant-mPLoc online tools. Characterization of the Edkawy tomato cultivar and isolation and identification of such transcription factors will help in the engineering of tomato plants with abiotic stress tolerance

    Endogenous overexpression of Populus MYB186 increases trichome density, improves insect pest resistance, and impacts plant growth

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    Trichomes are specialized epidermal cells that generally play a role in reducing transpiration and act as a deterrent to herbivory. In a screen of activation-tagged Populus tremula  ×  Populus alba 717-1B4 trees, we identified a mutant line, fuzzy , with increased foliar trichome density. This mutant also had a 35% increase in growth rate and a 200% increase in the rate of photosynthesis as compared with wild-type poplar. The fuzzy mutant had significant resistance to feeding by larvae of the white-spotted tussock moth ( Orgyia leucostigma ), a generalist insect pest of poplar trees. The fuzzy trichome phenotype is attributable to activation tagging and increased expression of the gene encoding PtaMYB186 , which is related to Arabidopsis thaliana MYB106 , a known regulator of trichome initiation. The fuzzy phenotype can be recapitulated by overexpressing PtaMYB186 in poplar. PtaMYB186 overexpression results in reconfiguration of the poplar transcriptome, with changes in the transcript abundance of suites of genes that are related to trichome differentiation. It is notable that a plant with misexpression of a gene responsible for trichome development also had altered traits related to growth rate and pest resistance, suggesting that non-intuitive facets of plant development might be useful targets for plant improvement.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79232/1/TPJ_4343_sm_FigsS1-S3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/79232/2/j.1365-313X.2010.04343.x.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/79232/3/TPJ_4343_sm_TableS5.pd

    Genome sequencing and population genomic analyses provide insights into the adaptive landscape of silver birch

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    Silver birch (Betula pendula) is a pioneer boreal tree that can be induced to flower within 1 year. Its rapid life cycle, small (440-Mb) genome, and advanced germplasm resources make birch an attractive model for forest biotechnology. We assembled and chromosomally anchored the nuclear genome of an inbred B. pendula individual. Gene duplicates from the paleohexaploid event were enriched for transcriptional regulation, whereas tandem duplicates were overrepresented by environmental responses. Population resequencing of 80 individuals showed effective population size crashes at major points of climatic upheaval. Selective sweeps were enriched among polyploid duplicates encoding key developmental and physiological triggering functions, suggesting that local adaptation has tuned the timing of and cross-talk between fundamental plant processes. Variation around the tightly-linked light response genes PHYC and FRS10 correlated with latitude and longitude and temperature, and with precipitation for PHYC. Similar associations characterized the growth-promoting cytokinin response regulator ARR1, and the wood development genes KAK and MED5A.Peer reviewe

    Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

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    Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate

    Overview of the JET ITER-like wall divertor

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    Impact of fast ions on density peaking in JET: fluid and gyrokinetic modeling

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    The effect of fast ions on turbulent particle transport, driven by ion temperature gradient (ITG)/ trapped electron mode turbulence, is studied. Two neutral beam injection (NBI) heated JET discharges in different regimes are analyzed at the radial position ρt_{t}=0.6, one of them an L-mode and the other one an H-mode discharge. Results obtained from the computationally efficient fluid model EDWM and the gyro-fluid model TGLF are compared to linear and nonlinear gyrokinetic GENE simulations as well as the experimentally obtained density peaking. In these models, the fast ions are treated as a dynamic species with a Maxwellian background distribution. The dependence of the zero particle flux density gradient (peaking factor) on fast ion density, temperature and corresponding gradients, is investigated. The simulations show that the inclusion of a fast ion species has a stabilizing influence on the ITG mode and reduces the peaking of the main ion and electron density profiles in the absence of sources. The models mostly reproduce the experimentally obtained density peaking for the L-mode discharge whereas the H-mode density peaking is significantly underpredicted, indicating the importance of the NBI particle source for the H-mode density profile

    Current Research into Applications of Tomography for Fusion Diagnostics

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    Retrieving spatial distribution of plasma emissivity from line integrated measurements on tokamaks presents a challenging task due to ill-posedness of the tomography problem and limited number of the lines of sight. Modern methods of plasma tomography therefore implement a-priori information as well as constraints, in particular some form of penalisation of complexity. In this contribution, the current tomography methods under development (Tikhonov regularisation, Bayesian methods and neural networks) are briefly explained taking into account their potential for integration into the fusion reactor diagnostics. In particular, current development of the Minimum Fisher Regularisation method is exemplified with respect to real-time reconstruction capability, combination with spectral unfolding and other prospective tasks
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