1,437 research outputs found

    The observational constraints on the flat ϕ\phiCDM models

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    Most dark energy models have the Λ\LambdaCDM as their limit, and if future observations constrain our universe to be close to Λ\LambdaCDM Bayesian arguments about the evidence and the fine-tuning will have to be employed to discriminate between the models. Assuming a baseline Λ\LambdaCDM model we investigate a number of quintessence and phantom dark energy models, and we study how they would perform when compared to observational data, such as the expansion rate, the angular distance, and the growth rate measurements, from the upcoming Dark Energy Spectroscopic Instrument (DESI) survey. We sample posterior likelihood surfaces of these dark energy models with Monte Carlo Markov Chains while using central values consistent with the Planck Λ\LambdaCDM universe and covariance matrices estimated with Fisher information matrix techniques. We find that for this setup the Bayes factor provides a substantial evidence in favor of the Λ\LambdaCDM model over most of the alternatives. We also investigated how well the CPL parametrization approximates various scalar field dark energy models, and identified the location for each dark energy model in the CPL parameter space.Comment: 11 pages, 5 figures; 4 tables; published in European Journal of Physics

    Primordial magnetic helicity evolution with a homogeneous magnetic field from inflation

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    Motivated by a scenario of magnetogenesis in which a homogeneous magnetic field is generated during inflation, we study the magnetohydrodynamic evolution of the primordial plasma motions for two kinds of initial conditions -- (i) a spatially homogeneous field with an unlimited correlation length, and (ii) a zero flux scale-invariant statistically homogeneous magnetic field. In both cases, we apply, for a short initial time interval, monochromatic forcing at a certain wave number so that the correlation length is finite, but much smaller than the typical length scale of turbulence. In particular, we investigate the decay of nonhelical and helical hydromagnetic turbulence. We show that, in the presence of a homogeneous magnetic field, the decay of helical and nonhelical small-scale fields can occur rapidly. This is a special property of a system with a perfectly homogeneous magnetic field, which is sometimes considered as a local approximation to a slowly varying background field. It can never change and acts as an imposed magnetic field. This is in a sharp contrast to the case of a statistically homogeneous magnetic field, where we recover familiar decay properties: a much slower decay of magnetic energy and a faster growth of the correlation length, especially in the case with magnetic felicity. The result suggests that a homogeneous magnetic field, if generated during inflation, should persist under the influence of small-scale fields and could be the origin of the large-scale magnetic field in the Universe.Comment: 16 pages, 7 figures, 1 table. Journal versio

    Biochar-amended potting medium reduces the susceptibility of rice to root-knot nematode infections

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    Background: Biochar is a solid coproduct of biomass pyrolysis, and soil amended with biochar has been shown to enhance the productivity of various crops and induce systemic plant resistance to fungal pathogens. The aim of this study was to explore the ability of wood biochar to induce resistance to the root-knot nematode (RKN) Meloidogyne graminicola in rice (Oryza sativa cv. Nipponbare) and examine its histochemical and molecular impact on plant defense mechanisms. Results: A 1.2 % concentration of biochar added to the potting medium of rice was found to be the most effective at reducing nematode development in rice roots, whereas direct toxic effects of biochar exudates on nematode viability, infectivity or development were not observed. The increased plant resistance was associated with biochar-primed H2O2 accumulation as well as with the transcriptional enhancement of genes involved in the ethylene (ET) signaling pathway. The increased susceptibility of the Ein2b-RNAi line, which is deficient in ET signaling, further confirmed that biochar-induced priming acts at least partly through ET signaling. Conclusion: These results suggest that biochar amendments protect rice plants challenged by nematodes. This priming effect partially depends on the ET signaling pathway and enhanced H2O2 accumulation

    Health and Nutrition in Vermont Children

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    Introduction. The AHA (American Heart Association) supports legislation in Ver- mont ensuring that restaurants’ children’s menu meals meet certain nutritional standards. This study investigated Vermont parents’ attitudes towards both dining at restaurants with their children and potential legislation to improve nutritional standards of restaurant food. Methods. An anonymous 21-question survey for parents with children under age 18 was distributed electronically to local organizations via Facebook groups and email, and as paper questionnaires at the Community Health Center of Burlington. Questions probed parents’ overall attitudes surrounding their children’s health, habits pertaining to eating at restaurants, and attitudes towards legislation to ensure healthier options for kids at restaurants. Results were analyzed to look for dominant themes and determine differences between subgroups. Results. 98% of survey participants agreed or strongly agreed that their children’s eating habits are important to them. When asked if they would support legislation to set nutrition standards on children’s menu meals in Vermont, 73% agreed or strongly agreed. Most survey participants eat at a restaurant once per week or less (95%). 53% of survey participants agreed or strongly agreed that there were enough restaurants with healthy kids’ meals in their area. Responses did not differ by county. Conclusion. Vermont parents are concerned about their children’s diets and acknowledge connections between nutrition, obesity, and overall health. Parents favor restaurants providing more nutritional items on children’s menus and support the AHA’s proposed standards. Next steps include investigating any financial impact on restaurants and studying nutritional standards in school cafeterias in Vermont.https://scholarworks.uvm.edu/comphp_gallery/1257/thumbnail.jp

    Low-Frequency Noise Spectroscopy of Charge-Density-Wave Phase Transitions in Vertical Quasi-2D Devices

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    We report results regarding the electron transport in vertical quasi-2D layered 1T-TaS2 charge-density-wave devices. The low-frequency noise spectroscopy was used as a tool to study changes in the cross-plane electrical characteristics of the quasi-2D material below room temperature. The noise spectral density revealed strong peaks - changing by more than an order-of-magnitude - at the temperatures closely matching the electrical resistance steps. Some of the noise peaks appeared below the temperature of the commensurate to nearly-commensurate charge-density-wave transition, possibly indicating the presence of the debated "hidden" phase transitions. These results confirm the potential of the noise spectroscopy for investigations of electron transport and phase transitions in novel materials.Comment: 16 pages; 5 figure

    The Past, Present, and Future of the Chinese Home: An Architectural Study of the Relationship Between Politics, Culture, and Domestic Space

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    This thesis analyzes the oscillating cause and effect between State, citizen, and architecture by studying the relationship between politics and domestic spaces in China. It explores the development of China from the beginning of the twentieth century through the present and into a speculative future to argue that wider sociopolitical changes are reflected in the detailed and intimate spaces of the home, and conversely, that the home can act as an agent of political resistance. The timeline in question represents a unique and tumultuous era in the development of modern China, one which dramatically changed the way people in China built their homes, and in turn, lived their lives. By imagining a speculative future condition in which China has undergone another major political and cultural shift, this thesis will consider the past in order to propose a speculative trajectory for the future of domestic Chinese architecture

    The Role of Processing Fluency in Source Memory and Metamemory

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    Processing fluency influences various judgements in memory and cognition such as fluency-based familiarity in tests of item recognition memory. However, less is known about the interplay between fluency and source information in recognition memory and metamemory phenomena. The present thesis investigated the relationship between perceptual fluency and the accuracy of source memory decisions (Experiments 1-3b), as well as the contribution of perceptual fluency to the font size effect (i.e., the tendency to rate larger font words as easier to remember than smaller font words, despite font size having no effect on retention performance) in judgements of learning (Experiments 4-6). Fluency was indexed via identification response times (RTs) derived from adapted versions of the continuous identification (CID) task, in which stimuli gradually clarified through progressive demasking. Identification RTs were faster in trials with correct retrieval of source information compared to trials for which source could not be accurately retrieved, and JOLs were indirectly increased by the faster identification RTs associated with a larger font size. These findings suggest that fluency is related both to source memory and metamemory judgements

    The Diploid Genome Sequence of an Individual Human

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    Presented here is a genome sequence of an individual human. It was produced from ~32 million random DNA fragments, sequenced by Sanger dideoxy technology and assembled into 4,528 scaffolds, comprising 2,810 million bases (Mb) of contiguous sequence with approximately 7.5-fold coverage for any given region. We developed a modified version of the Celera assembler to facilitate the identification and comparison of alternate alleles within this individual diploid genome. Comparison of this genome and the National Center for Biotechnology Information human reference assembly revealed more than 4.1 million DNA variants, encompassing 12.3 Mb. These variants (of which 1,288,319 were novel) included 3,213,401 single nucleotide polymorphisms (SNPs), 53,823 block substitutions (2-206 bp), 292,102 heterozygous insertion/deletion events (indels)(1-571 bp), 559,473 homozygous indels (1-82,711 bp), 90 inversions, as well as numerous segmental duplications and copy number variation regions. Non-SNP DNA variation accounts for 22% of all events identified in the donor, however they involve 74% of all variant bases. This suggests an important role for non-SNP genetic alterations in defining the diploid genome structure. Moreover, 44% of genes were heterozygous for one or more variants. Using a novel haplotype assembly strategy, we were able to span 1.5 Gb of genome sequence in segments >200 kb, providing further precision to the diploid nature of the genome. These data depict a definitive molecular portrait of a diploid human genome that provides a starting point for future genome comparisons and enables an era of individualized genomic information
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