651 research outputs found
A scheme with two large extra dimensions confronted with neutrino physics
We investigate a particle physics model in a six-dimensional spacetime, where
two extra dimensions form a torus. Particles with Standard Model charges are
confined by interactions with a scalar field to four four-dimensional branes,
two vortices accommodating ordinary type fermions and two antivortices
accommodating mirror fermions. We investigate the phenomenological implications
of this multibrane structure by confronting the model with neutrino physics
data.Comment: LATEX, 24 pages, 9 figures, minor changes in the tex
Efficiency of Single Nucleotide Polymorphisms to improve a genetic map of complex pedigree grapevines
A set of 47 SNP (single nucleotide polymorphisms) markers (Cabezas et al. 2011) was tested for their usefulness to improve a genetic map from the cross of GF.GA‑52-42 x 'Solaris' previously established with SSR markers (Schwander et al. 2012). 55.3 % of the SNPs showed informative segregation and 26 SNP markers were localized on 16 of the 19 linkage groups of grapevine. Five chromosome regions with large gaps of recombining SSR markers could be equipped by positioning a SNP marker there. One SNP marker, VV10992, was found linked to the major resistance locus Rpv10 and should be applicable for marker-assisted selection
Grapevine breeding under climate change: Applicability of a molecular marker linked to véraison
Viticulture is of high economic value. Traditional grapevine cultivars (Vitis vinifera L.) are used in adaptation to the climatic conditions from Northern to Southern European growing areas. However, the recent trend of global warming causes quality deficits due to a shift of the plant's development to earlier times in the year. As a consequence, premature ripening happens under warm temperatures and interferes with the balanced accumulation of sugars, acids, aroma profiles and berry coloration. Modern grapevine breeding is challenged to include the ripening behavior as an important trait (besides pathogen resistance and other characteristics) into the development of novel cultivars well suited for sustainable viticulture. Breeders nowadays apply molecular markers to follow the introgression of desired traits on the genetic level. Previous work has identified a molecular tag on grapevine chromosome 16 strongly linked to the time of véraison, the start of the second phase of berry ripening, in a segregating cross population. In this study we analyzed the transferability of this marker to a set of 36 grapevine cultivars commonly used in German viticulture. Association analysis verified the predictive character of the time point of véraison for maturation time and confirmed the diagnostic potential of the véraison-linked marker in this extended set of cultivars
Chlorine isotope composition in chlorofluorocarbons CFC-11, CFC-12 and CFC-113 in firn, stratospheric and tropospheric air
The stratospheric degradation of chlorofluorocarbons (CFCs) releases chlorine, which is a major contributor to the destruction of stratospheric ozone (O3). A recent study reported strong chlorine isotope fractionation during the breakdown of the most abundant CFC (CFC-12, CCl2F2, Laube et al., 2010a), similar to effects seen in nitrous oxide (N2O). Using air archives to obtain a long-term record of chlorine isotope ratios in CFCs could help to identify and quantify their sources and sinks. We analyse the three most abundant CFCs and show that CFC-11 (CCl3F) and CFC-113 (CClF2CCl2F) exhibit significant stratospheric chlorine isotope fractionation, in common with CFC-12. The apparent isotope fractionation (εapp) for mid- and high-latitude stratospheric samples are (-2.4±0.5) ‰ and (-2.3±0.4) ‰ for CFC-11, (-12.2±1.6) ‰ and (-6.8±0.8) ‰ for CFC-12 and (-3.5±1.5) ‰ and (-3.3±1.2) ‰ for CFC-113, respectively. Assuming a constant isotope composition of emissions, we calculate the expected trends in the tropospheric isotope signature of these gases based on their stratospheric 37Cl enrichment and stratosphere-troposphere exchange. We compare these projections to the long-term δ(37Cl) trends of all three CFCs, measured on background tropospheric samples from the Cape Grim air archive (Tasmania, 1978 – 2010) and tropospheric firn air samples from Greenland (NEEM site) and Antarctica (Fletcher Promontory site). From 1970 to the present-day, projected trends agree with tropospheric measurements, suggesting that within analytical uncertainties a constant average emission isotope delta is a compatible scenario. The measurement uncertainty is too high to determine whether the average emission isotope delta has been affected by changes in CFC manufacturing processes, or not. Our study increases the suite of trace gases amenable to direct isotope ratio measurements in small air volumes (approximately 200 ml), using a single-detector gas chromatography-mass spectrometry system
A view into American grapevine history: Vitis vinifera cv. 'Sémillon' is an ancestor of 'Catawba' and 'Concord'
The Vitis vinifera background of 'Catawba' and 'Concord' was investigated by using SSR analysis: 'Sémillon' was shown to be an ancestor of 'Catawba', while the wild parent remains unknown. 'Concord' was confirmed to be an offspring of 'Catawba' and another unknown wild parent. Since these two important American varieties most likely resulted from random natural crosses and successful selection, the original, wild growing wild donors remain unknown
Mapping the conformations of biological assemblies
Mapping conformational heterogeneity of macromolecules presents a formidable
challenge to X-ray crystallography and cryo-electron microscopy, which often
presume its absence. This has severely limited our knowledge of the
conformations assumed by biological systems and their role in biological
function, even though they are known to be important. We propose a new approach
to determining to high resolution the three-dimensional conformations of
biological entities such as molecules, macromolecular assemblies, and
ultimately cells, with existing and emerging experimental techniques. This
approach may also enable one to circumvent current limits due to radiation
damage and solution purification.Comment: 14 pages, 6 figure
Accelerating growth of HFC-227ea (1,1,1,2,3,3,3-heptafluoropropane) in the atmosphere
We report the first measurements of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), a substitute for ozone depleting compounds, in air samples originating from remote regions of the atmosphere and present evidence for its accelerating growth. Observed mixing ratios ranged from below 0.01 ppt in deep firn air to 0.59 ppt in the current northern mid-latitudinal upper troposphere. Firn air samples collected in Greenland were used to reconstruct a history of atmospheric abundance. Year-on-year increases were deduced, with acceleration in the growth rate from 0.029 ppt per year in 2000 to 0.056 ppt per year in 2007. Upper tropospheric air samples provide evidence for a continuing growth until late 2009. Furthermore we calculated a stratospheric lifetime of 370 years from measurements of air samples collected on board high altitude aircraft and balloons. Emission estimates were determined from the reconstructed atmospheric trend and suggest that current "bottom-up" estimates of global emissions for 2005 are too high by a factor of three
Rapid growth of HFC-227ea (1,1,1,2,3,3,3-Heptafluoropropane) in the atmosphere
We report the first measurements of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), a substitute for ozone depleting compounds, in remote regions of the atmosphere and present evidence for its rapid growth. Observed mixing ratios ranged from below 0.01 ppt in deep firn air to 0.59 ppt in the northern mid-latitudinal upper troposphere. Firn air samples collected in Greenland were used to reconstruct a history of atmospheric abundance. Year-on-year increases were deduced, with acceleration in the growth rate from 0.026 ppt per year in 2000 to 0.057 ppt per year in 2007. Upper tropospheric air samples provide evidence for a continuing growth until late 2009. Fur- thermore we calculated a stratospheric lifetime of 370 years from measurements of air samples collected on board high altitude aircraft and balloons. Emission estimates were determined from the reconstructed atmospheric trend and suggest that current "bottom-up" estimates of global emissions for 2005 are too high by more than a factor of three
First-Digit Law in Nonextensive Statistics
Nonextensive statistics, characterized by a nonextensive parameter , is a
promising and practically useful generalization of the Boltzmann statistics to
describe power-law behaviors from physical and social observations. We here
explore the unevenness of the first digit distribution of nonextensive
statistics analytically and numerically. We find that the first-digit
distribution follows Benford's law and fluctuates slightly in a periodical
manner with respect to the logarithm of the temperature. The fluctuation
decreases when increases, and the result converges to Benford's law exactly
as approaches 2. The relevant regularities between nonextensive statistics
and Benford's law are also presented and discussed.Comment: 11 pages, 3 figures, published in Phys. Rev.
The catalytic role of glutathione transferases in heterologous anthocyanin biosynthesis
Anthocyanins are ubiquitous plant pigments used in a variety of technological applications. Yet, after over a century of research, the penultimate biosynthetic step to anthocyanidins attributed to the action of leucoanthocyanidin dioxygenase has never been efficiently reconstituted outside plants, preventing the construction of heterologous cell factories. Through biochemical and structural analysis, here we show that anthocyanin-related glutathione transferases, currently implicated only in anthocyanin transport, catalyse an essential dehydration of the leucoanthocyanidin dioxygenase product, flavan-3,3,4-triol, to generate cyanidin. Building on this knowledge, introduction of anthocyanin-related glutathione transferases into a heterologous biosynthetic pathway in baker's yeast results in >35-fold increased anthocyanin production. In addition to unravelling the long-elusive anthocyanin biosynthesis, our findings pave the way for the colourants' heterologous microbial production and could impact the breeding of industrial and ornamental plants
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