981 research outputs found

    Two Nucleon-States in a Chiral Quark-Diquark Model

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    We study the ground and first excited states of nucleons in a chiral quark-diquark model. We include two quark-diquark channels of the scalar-isoscalar and axial-vector-isovector types for the nucleon states. The diquark correlation violating the spin-flavor SU(4)SF_{SF} symmetry allows to treat the two quark-diquark channels independently. Hence the two states appear as the superpositions of the two quark-diquark channels; one is the nucleon and the other is a state which does not appear in the SU(4)SF_{SF} quark models. With a reasonable choice of model parameters, the mass of the excited state appears at around 1.5 GeV, which we identify with the Roper resonance N(1440).Comment: 11 pages, 5 figures. Errors are corrected. Conclusions are not affecte

    Reduced OoB Emission and PAPR Using Partial-OSLM technique in 5G UFMC Systems

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    Universal-filtered multi-carrier (UFMC) waveformis considered as a potential candidate for next generation wirelesssystems due to its robustness against inter-carrier interference(ICI) and the low latency required in 5G systems. In this paper, apulse shaping approaches in UFMC technique is studied to reducethe spectral leakage into nearby sub-bands. The performance ofvarious types of window functions such as Chebychev, Hamming,Hanning and Blackman with UFMC are compared. This leadsto different coefficients and attenuation shapes, that enabledto choose the proper window function. Finally, a new selectivemapping (SLM) peak to average power ratio (PAPR) reductiontechnique is proposed to enhance the UFMC system performance.Results show that the BER performance of UFMC with allwindows functions are the same. However, Blackman windowfunction has a higher attenuation for sidebands compared withothers

    Transformer Faults Classification Based on Convolution Neural Network

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    This paper studies the latest advances made in Deep Learning (DL) methods utilized for transformer inrush and fault currents classification. Inrush and fault currents at different operating conditions, initial flux and fault type are simulated. This paper presents a technique for the classification of power transformer faults which is based on a DL method called convolutional neural network (CNN) and compares it with traditional artificial neural network (ANN) and other techniques. The inrush and fault current signals of the transformer are simulated within MATLAB by using Fourier analyzers that provides the 2nd harmonic signal. The 2nd harmonic peak and variance statistic values of input signals of the three phases of transformer are used at different operating conditions. The resulted values are aggregated into a dataset to be used as an input for the CNN model, then training and testing the CNN model is performed. Consequently, it is obvious that the CNN algorithm achieves a better performance compared to other algorithms. This study helps with easy discrimination between normal signals and faulty signals and to determine the type of the fault to clear it easily

    Comments on Diquarks, Strong Binding and a Large Hidden QCD Scale

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    We present arguments regarding diquarks possible role in low-energy hadron phenomenology that escaped theorists' attention so far. Good diquarks, i.e. the 0+0^{+} states of two quarks, are argued to have a two-component structure with one of the components peaking at distances several times shorter than a typical hadron size (a short-range core). This can play a role in solving two old puzzles of the 't Hooft 1/N expansion: strong quark mass dependence of the vacuum energy density and strong violations of the Okubo-Zweig-Iizuka (OZI) rule in the quark-antiquark 0±0^\pm channels. In both cases empiric data defy 't Hooft's 1/N suppression. If good diquarks play a role at an intermediate energy scale they ruin 't Hoofts planarity because of their mixed-flavor composition. This new scale associated with the good diquarks may be related to a numerically large scale discovered in [V. Novikov, M. Shifman, A. Vainshtein and V. Zakharov, Nucl. Phys. B 191, 301 (1981)] in a number of phenomena mostly related to vacuum quantum numbers and 0±0^\pm glueball channels. If SU(3)color_{\rm color} of bona fide QCD is replaced by SU(2)color_{\rm color}, diquarks become well-defined gauge invariant objects. Moreover, there is an exact symmetry relating them to pions. In this limit predictions regarding good diquarks are iron-clad. If passage from SU(2)color_{\rm color} to SU(3)color_{\rm color} does not lead to dramatic disturbances, these predictions remain qualitatively valid in bona fide QCD.Comment: 18 pages, 3 figures; journal version, minor change

    JPJ^P Assignments of Λc+\Lambda_c^+ Baryons

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    The "good" diquark is employed to study Λc+\Lambda_c^{+} baryons within a mass loaded flux tube model. The study indicates that all Λc+\Lambda_c^{+} baryons candidates in the 2008 review by the Particle Data Group (PDG) are well described in the mass loaded flux tube model. The quantum numbers JPJ^P of these Λc+\Lambda_c^{+} candidates are assigned. If Λc(2765)+\Lambda_c(2765)^{+} is an orbitally excited Λc+\Lambda^+_c, it is likely the JP=32+J^P={3\over 2}^+ one. If Λc(2765)+\Lambda_c(2765)^+ is an orbitally excited Σc\Sigma_c, there ought to be another JP=32+J^P={3\over 2}^+ Λc+\Lambda^+_c with mass 2770\approx 2770 MeV. In the model, there exists no JP=12+J^P={1\over 2}^+ Λc(2700)+\Lambda_c(\approx 2700)^+ predicted in existing literature. Λc(2940)+\Lambda_c(2940)^{+} is very possible the orbitally excited baryon with JP=52J^P={5\over 2}^-.Comment: 4 pages, 3 tables, RevTex, Two typos correcte

    ActDES- a Curated Actinobacterial Database for Evolutionary Studies

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    Actinobacteria is a large and diverse phylum of bacteria that contains medically and ecologically relevant organisms. Many members are valuable sources of bioactive natural products and chemical precursors that are exploited in the clinic and made using the enzyme pathways encoded in their complex genomes. Whilst the number of sequenced genomes has increased rapidly in the last 20 years, the large size, complexity and high G+C content of many actinobacterial genomes means that the sequences remain incomplete and consist of large numbers of contigs with poor annotation, which hinders large-scale comparative genomic and evolutionary studies. To enable greater understanding and exploitation of actinobacterial genomes, specialized genomic databases must be linked to high-quality genome sequences. Here, we provide a curated database of 612 high-quality actinobacterial genomes from 80 genera, chosen to represent a broad phylogenetic group with equivalent genome re-annotation. Utilizing this database will provide researchers with a framework for evolutionary and metabolic studies, to enable a foundation for genome and metabolic engineering, to facilitate discovery of novel bioactive therapeutics and studies on gene family evolution. This article contains data hosted by Microreact

    Disconnected gas transport in steady‐state three‐phase flow

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    We use high-resolution three-dimensional X-ray microtomography to investigate fluid displacement during steady-state three-phase flow in a cm-sized water-wet sandstone rock sample. The pressure differential across the sample is measured which enables the determination of relative permeability; capillary pressure is also estimated from the interfacial curvature. Though the measured relative permeabilities are consistent, to within experimental uncertainty, with values obtained without imaging on larger samples, we discover a unique flow dynamics. The most non-wetting phase (gas) is disconnected across the system: gas flows by periodically opening critical flow pathways in intermediate-sized pores. While this phenomenon has been observed in two-phase flow, here it is significant at low flow rates, where capillary forces dominate at the pore-scale. Gas movement proceeds in a series of double and multiple displacement events. Implications for the design of three-phase flow processes and current empirical models are discussed: the traditional conceptualization of three-phase dynamics based on analogies to two-phase flow vastly over-estimates the connectivity and flow potential of the gas phase

    Whole genome sequencing reveals widespread distribution of typhoidal toxin genes and VirB/D4 plasmids in bovine-associated nontyphoidal Salmonella

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    Aedes aegypti is the primary urban mosquito vector of viruses causing dengue, Zika and chikungunya fevers –for which vaccines and efective pharmaceuticals are still lacking. Current strategies to suppress arbovirus outbreaks include removal of larval-breeding sites and insecticide treatment of larval and adult populations. Insecticidal control of Ae. aegypti is challenging, due to a recent rapid global increase in knockdown-resistance (kdr) to pyrethroid insecticides. Widespread, heavy use of pyrethroid spacesprays has created an immense selection pressure for kdr, which is primarily under the control of the voltage-gated sodium channel gene (vgsc). To date, eleven replacements in vgsc have been discovered, published and shown to be associated with pyrethroid resistance to varying degrees. In Mexico, F1,534C and V1,016I have co-evolved in the last 16 years across Ae. aegypti populations. Recently, a novel replacement V410L was identifed in Brazil and its efect on vgsc was confrmed by electrophysiology. Herein, we screened V410L in 25 Ae. aegypti historical collections from Mexico, the frst heterozygote appeared in 2002 and frequencies have increased in the last 16 years alongside V1,016I and F1,534C. Knowledge of the specifc vgsc replacements and their interaction to confer resistance is essential to predict and to develop strategies for resistance management

    Expanding Primary Metabolism Helps Generate the Metabolic Robustness To Facilitate Antibiotic Biosynthesis in Streptomyces

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    Abstract The expansion of the genetic repertoire of an organism by gene duplication or horizontal gene transfer (HGT) can aid adaptation. Streptomyces bacteria are prolific producers of bioactive specialized metabolites that have adaptive functions in nature and have found extensive utility in human medicine. Whilst the biosynthesis of these specialized metabolites is directed by dedicated biosynthetic gene clusters, little attention has been focussed on how these organisms have evolved robustness into their genomes to facilitate the metabolic plasticity required to provide chemical precursors for biosynthesis during the complex metabolic transitions from vegetative growth to specialized metabolite production and sporulation. Here we examine genetic redundancy in Actinobacteria and show that specialised metabolite producing bacterial families exhibit gene family expansion in primary metabolism. Focussing on a gene duplication event we show that the two pyruvate kinases in the genome of S. coelicolor arose by an ancient duplication event and that each have evolved altered enzymatic kinetics, with Pyk1 having a 20-fold higher Kcat than Pyk2 (4703 sec-1 compared to 215 sec-1 respectively) yet both are constitutively expressed. The pyruvate kinase mutants were also found to be compromised in terms of fitness when compared to wild-type Streptomyces. These data suggest that expanding gene familes can help maintain cell functionality during metabolic perturbation such as nutrient limitation and/or specialized metabolite production. Importance The rise of antimicrobial resistant infections has prompted a resurgence in interest in understanding the production of specialized metabolites by Streptomyces such as antibiotics. The presence of multiple genes encoding the same enzymatic function is an aspect of Streptomyces biology that has received little attention, however understanding how the metabolic expansion influences these organisms can help enhance production of clinically useful molecules. Here we show that expanding the number of pyruvate kinases enables metabolic adaptation, increases strain fitness and represents an excellent target for metabolic engineering of industrial specialized metabolite producing bacteria and the activation of cryptic specialized metabolites
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