3,243 research outputs found

    Conformal and non Conformal Dilaton Gravity

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    The quantum dynamics of the gravitational field non-minimally coupled to an (also dynamical) scalar field is studied in the {\em broken phase}. For a particular value of the coupling the system is classically conformal, and can actually be understood as the group averaging of Einstein-Hilbert's action under conformal transformations. Conformal invariance implies a simple Ward identity asserting that the trace of the equation of motion for the graviton is the equation of motion of the scalar field. We perform an explicit one-loop computation to show that the DeWitt effective action is not UV divergent {\em on shell} and to find that the Weyl symmetry Ward identity is preserved {\em on shell} at that level. We also discuss the fate of this Ward identity at the two-loop level --under the assumption that the two-loop UV divergent part of the effective action can be retrieved from the Goroff-Sagnotti counterterm-- and show that its preservation in the renormalized theory requires the introduction of counterterms which exhibit a logarithmic dependence on the dilaton field.Comment: LateX, 50 pages. Several points clarified; references added. New section on Weyl invariant renormalisation adde

    A Renormalization Group Analysis of the NCG constraints m_{top} = 2\,m_W}, mHiggs=3.14mWm_{Higgs} = 3.14 \, m_W

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    We study the evolution under the renormalization group of the restrictions on the parameters of the standard model coming from Non-Commutative Geometry, namely mtop=2mWm_{top} = 2\,m_W and mHiggs=3.14mWm_{Higgs} = 3.14 \, m_W. We adopt the point of view that these relations are to be interpreted as {\it tree level} constraints and, as such, can be implemented in a mass independent renormalization scheme only at a given energy scale μ0\mu_0. We show that the physical predictions on the top and Higgs masses depend weakly on μ0\mu_0.Comment: 7 pages, FTUAM-94/2, uses harvma

    Use of tire derived aggregate in tunnel cut-and-cover

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    A case-history is reported in which tire derived aggregate (TDA) was successfully applied to reduce the weight of fill upon a cut-and-cover railway tunnel. Subsequent 3D numerical analyses are used to explore the effect of different assumptions about the constitutive model of the TDA material. Alternative dispositions of TDA around the tunnel section are also examined. Reductions of up to 60% in lining bending moment may be achieved. For the case analyzed the elastic description of the TDA has little influence on tunnel lining loads, although is important for fill settlement estimates.Peer ReviewedPostprint (author's final draft

    Genomic organization of nucleolin gene in carp fish: Evidence for several genes

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    http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602006000200017&lng=es&nrm=isoThe protein nucleolin, functionally involved in the main steps of ribosome biogenesis, is codified by a single copy gene in mammals. Here we report that at least three different genes codify for this protein in carp fish (Cyprinus carpio). This is the first description of the genomic organization of nucleolin in a teleost. The carp nucleolin gene includes 8.8 kb and contains 16 exons. Promoter cis regulatory elements are similar to constitutive genes, i.e., a putative TATA box, three G/C boxes, and three pyrimidine-rich boxes. As in other species, carp nucleolin gene introns host three snoRNA codifying sequences: U23 from the H/ACA family and two C/D box snoRNAs, U20 and U82. Both U20 and U82 span a complementary sequence with carp 18S rRNA. Additionally, we identified two cDNAs coding for nucleolin, confirming the existence of several nucleolin genes in carp. Amino acidderived sequence from carp cDNAs differ from mammal protein because they span additional acidic domains at the amino end, whose functional significance remains unclear. We performed amino acid sequence comparison and phylogenetic analyses showing that the three isoforms of carp nucleolin, which we describe herein, cluster in two groups. cNUC1 probably diverges from cNUC2 and cNUC3 as result of ancestral fish-specific genome duplication, indeed C. carpio is a tetraploid fish

    Quantum autoencoders via quantum adders with genetic algorithms

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    The quantum autoencoder is a recent paradigm in the field of quantum machine learning, which may enable an enhanced use of resources in quantum technologies. To this end, quantum neural networks with less nodes in the inner than in the outer layers were considered. Here, we propose a useful connection between approximate quantum adders and quantum autoencoders. Specifically, this link allows us to employ optimized approximate quantum adders, obtained with genetic algorithms, for the implementation of quantum autoencoders for a variety of initial states. Furthermore, we can also directly optimize the quantum autoencoders via genetic algorithms. Our approach opens a different path for the design of quantum autoencoders in controllable quantum platforms

    Phenomenological based model of hydrogen production using an alkaline self-pressurized electrolyzer

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    © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The aim of this work is to develop the phenomenological based modeling of a self-pressurized alkaline electrolyser with the objective of predicting the cross-contamination of the gases produced. A proposed model, built in Matlab®, represents the dynamical evolution in real electrolysers, and anticipates operational variables: level, pressure and all concentrations. Dynamic responses in the concentrations of the electrolytic cell, and variations in both level and pressure at the chamber due to the change in current and diffusivity, are reported. The equations by which the variables can be computed are also presented. The proposed model is ready for the corresponding adjustment of parameters based on experimental measurements taken from an available prototype and through a suitable identification process.Peer ReviewedPostprint (author's final draft

    Supervised Quantum Learning without Measurements

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    We propose a quantum machine learning algorithm for efficiently solving a class of problems encoded in quantum controlled unitary operations. The central physical mechanism of the protocol is the iteration of a quantum time-delayed equation that introduces feedback in the dynamics and eliminates the necessity of intermediate measurements. The performance of the quantum algorithm is analyzed by comparing the results obtained in numerical simulations with the outcome of classical machine learning methods for the same problem. The use of time-delayed equations enhances the toolbox of the field of quantum machine learning, which may enable unprecedented applications in quantum technologies

    The pleiotropic transcriptional regulator NlpR contributes to the modulation of nitrogen metabolism, lipogenesis and triacylglycerol accumulation in oleaginous rhodococci

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    The regulatory mechanisms involved in lipogenesis and triacylglycerol (TAG) accumulation are largely unknown in oleaginous rhodococci. In this study a regulatory protein (here called NlpR: Nitrogen lipid Regulator), which contributes to the modulation of nitrogen metabolism, lipogenesis and triacylglycerol accumulation in oleaginous rhodococci was identified. Under nitrogen deprivation conditions, in which TAG accumulation is stimulated, the nlpR gene was significantly upregulated, whereas a significant decrease of its expression and TAG accumulation occurred when cerulenin was added. The nlpR disruption negatively affected the nitrate/nitrite reduction as well as lipid biosynthesis under nitrogen-limiting conditions. In contrast, its overexpression increased TAG production during cultivation of cells in nitrogen-rich media. A putative ‘NlpR-binding motif’ upstream of several genes related to nitrogen and lipid metabolisms was found. The nlpR disruption in RHA1 strain led to a reduced transcription of genes involved in nitrate/nitrite assimilation, as well as in fatty acid and TAG biosynthesis. Purified NlpR was able to bind to narK, nirD, fasI, plsC and atf3 promoter regions. It was suggested that NlpR acts as a pleiotropic transcriptional regulator by activating of nitrate/nitrite assimilation genes and others genes involved in fatty acid and TAG biosynthesis, in response to nitrogen deprivation.Fil: Hernández, Martín Alejandro. Universidad Nacional de la Patagonia "san Juan Bosco". Instituto de Biociencias de la Patagonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biociencias de la Patagonia; ArgentinaFil: Lara, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gago, Gabriela Marisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gramajo, Hugo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Alvarez, Hector Manuel. Universidad Nacional de la Patagonia "san Juan Bosco". Instituto de Biociencias de la Patagonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biociencias de la Patagonia; Argentin
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