22,679 research outputs found

    Up Asymmetries From Exhilarated Composite Flavor Structures

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    We present a class of warped extra dimension (composite Higgs) models which conjointly accommodates the t\bar t forward-backward asymmetry observed at the Tevatron and the direct CP asymmetry in singly Cabibbo suppressed D decays first reported by the LHCb collaboration. We argue that both asymmetries, if arising dominantly from new physics beyond the Standard Model, hint for a flavor paradigm within partial compositeness models in which the right-handed quarks of the first two generations are not elementary fields but rather composite objects. We show that this class of models is consistent with current data on flavor and CP violating physics, electroweak precision observables, dijet and top pair resonance searches at hadron colliders. These models have several predictions which will be tested in forthcoming experiments. The CP asymmetry in D decays is induced through an effective operator of the form (\bar u c)_{V+A}(\bar s s)_{V+A} at the charm scale, which implies a larger CP asymmetry in the D^0\to K^+K^- rate relative the D^0\to \pi^+\pi^- channel. This prediction is distinctive from other Standard Model or dipole-based new physics interpretation of the LHCb result. CP violation in D-\bar D mixing as well as an an excess of dijet production of the LHC are also predicted to be observed in a near future. A large top asymmetry originates from the exchange of an axial resonance which dominantly produces left-handed top pairs. As a result a negative contribution to the lepton-based forward-backward asymmetry in t\bar t production, as well as O(10%) forward-backward asymmetry in b\bar b production above m_{b\bar b}\simeq 600GeV at the Tevatron is expected.Comment: 35 pages, 7 fig

    Analysis, Design and Implementation of Biodiesel Projects in Brazil

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    During the oil crisis of the seventies, Brazil has developed a successful program for gasoline substitution by ethanol (Proálcool). Nowadays the biomass accounts for 27% of total national energy consumed in Brazil and the ethanol participates with 40% of the total national fuel consumption of Otto cycle vehicles. In 2004, the National Program for the Production and Use of Biodiesel (Biodiesel Program) was launched. One priority of the Biodiesel Program is the inclusion of family agriculture and smallholders into the production chain. The Federal University of Viçosa (UFV) has developed a software for the analysis of biodiesel projects with the participation of family agriculture. Results of production chain analysis and economic indicators calculated by the Biosoft system have allowed identifying the regular supply of oil at competitive prices as the key point to the efficiency of biodiesel production chains. The use of oil cake as feedstock is the leverage point of chain performance. The meal sale can lead to a vegetal oil price reduction, without compromising farmers´ income, since they can be able to set up their own oil extraction plants. Coordination is then the critical element and has the potential to improve the performance of both the biodiesel industry and the animal production chain.Agribusiness, Agricultural and Food Policy, Farm Management, Food Consumption/Nutrition/Food Safety, Industrial Organization,

    An antibody raised against a pathogenic serpin variant induces mutant-like behaviour in the wild-type protein.

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    A monoclonal antibody (mAb) that binds to a transient intermediate may act as a catalyst for the corresponding reaction; here we show this principle can extend on a macro-molecular scale to the induction of mutant-like oligomerisation in a wild-type protein. Using the common, pathogenic Glu342Lys (Z) variant of α1-antitrypsin as antigen - whose native state is susceptible to the formation of a proto-oligomeric intermediate - we have produced a mAb (5E3) that increases the rate of oligomerisation of the wild-type (M) variant. Employing ELISA, gel shift, thermal stability and FRET time-course experiments, we show that mAb5E3 does not bind to the native state of α1-antitrypsin, but recognises a cryptic epitope in the vicinity of the post-helix A loop and strand 4C that is revealed upon transition to the polymerisation intermediate, and which persists in the ensuing oligomer. This epitope is not shared by loop-inserted monomeric conformations. We show the increased amenity to polymerisation by either the pathogenic Glu342Lys mutation or the binding of mAb5E3 occurs without affecting energetic barrier to polymerisation. As mAb5E3 also does not alter the relative stability of the monomer to intermediate, it acts in a manner similar to the Glu342Lys mutation, by facilitating the conformational interchange between these two states

    Prominent effect of soil network heterogeneity on microbial invasion

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    Using a network representation for real soil samples and mathematical models for microbial spread, we show that the structural heterogeneity of the soil habitat may have a very significant influence on the size of microbial invasions of the soil pore space. In particular, neglecting the soil structural heterogeneity may lead to a substantial underestimation of microbial invasion. Such effects are explained in terms of a crucial interplay between heterogeneity in microbial spread and heterogeneity in the topology of soil networks. The main influence of network topology on invasion is linked to the existence of long channels in soil networks that may act as bridges for transmission of microorganisms between distant parts of soil
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