2,157 research outputs found

    Quantum group symmetry of the Quantum Hall effect on the non-flat surfaces

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    After showing that the magnetic translation operators are not the symmetries of the QHE on non-flat surfaces , we show that there exist another set of operators which leads to the quantum group symmetries for some of these surfaces . As a first example we show that the su(2)su(2) symmetry of the QHE on sphere leads to suq(2)su_q(2) algebra in the equator . We explain this result by a contraction of su(2)su(2) . Secondly , with the help of the symmetry operators of QHE on the Pioncare upper half plane , we will show that the ground state wave functions form a representation of the suq(2)su_q(2) algebra .Comment: 8 pages,latex,no figur

    Necessary and sufficient conditions for local creation of quantum discord

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    We show that a local channel cannot create quantum discord (QD) for zero QD states of size d3d\geq3 if and only if either it is a completely decohering channel or it is a nontrivial isotropic channel. For the qubit case this propertiy is additionally characteristic to the completely decohering channel or the commutativity-preserving unital channel. In particular, the exact forms of the completely decohering channel and the commutativity-preserving unital qubit channel are proposed. Consequently, our results confirm and improve the conjecture proposed by X. Hu et al. for the case of d3d\geq3 and improve the result proposed by A. Streltsov et al. for the qubit case. Furthermore, it is shown that a local channel nullifies QD in any state if and only if it is a completely decohering channel. Based on our results, some protocols of quantum information processing issues associated with QD, especially for the qubit case, would be experimentally accessible.Comment: 8 page

    Efficacy of standard and low drift nozzles for insecticide applications against Aonidiella aurantii (Maskell) in citrus

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    Drift is especially critical when spraying fruit, vine and citrus orchards where pesticides are intensively used. In this context, cone low drift nozzles (LDN) intended for spraying tree crops, have been evaluated relating to cone standard nozzles (STN) in laboratory and deciduous fruit orchards (Van de Zande et al. 2012); (Planas et al., 2013)

    Combination of RNA interference and U1 inhibition leads to increased inhibition of gene expression

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    RNA interference (RNAi) has been revolutionary for the specific inhibition of gene expression. However, the application of RNAi has been hampered by the fact that many siRNAs induce dose-dependent unwanted secondary effects. Therefore, new methods to increase inhibition of gene expression with low doses of inhibitors are required. We have tested the combination of RNAi and U1i (U1 small nuclear RNA—snRNA—interference). U1i is based on U1 inhibitors (U1in), U1 snRNA molecules modified to target a pre-mRNA and inhibit its gene expression by blocking nuclear polyadenylation. The combination of RNAi and U1i resulted in stronger inhibition of reporter or endogenous genes than that obtained using either of the techniques alone. The increased inhibition observed is stable over time and allows higher inhibition than the best obtained with either of the inhibitors alone even with decreased doses of the inhibitors. We believe that the combination of RNAi and U1i will be of interest when higher inhibition is required or when potent inhibitors are not available. Also, the combination of these techniques would allow functional inhibition with a decreased dose of inhibitors, avoiding toxicity due to dose-dependent unwanted effects

    Adenovirus VA RNA-derived miRNAs target cellular genes involved in cell growth, gene expression and DNA repair

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    Adenovirus virus-associated (VA) RNAs are processed to functional viral miRNAs or mivaRNAs. mivaRNAs are important for virus production, suggesting that they may target cellular or viral genes that affect the virus cell cycle. To look for cellular targets of mivaRNAs, we first identified genes downregulated in the presence of VA RNAs by microarray analysis. These genes were then screened for mivaRNA target sites using several bioinformatic tools. The combination of microarray analysis and bioinformatics allowed us to select the splicing and translation regulator TIA-1 as a putative mivaRNA target. We show that TIA-1 is downregulated at mRNA and protein levels in infected cells expressing functional mivaRNAs and in transfected cells that express mivaRNAI-138, one of the most abundant adenoviral miRNAs. Also, reporter assays show that TIA-1 is downregulated directly by mivaRNAI-138. To determine whether mivaRNAs could target other cellular genes we analyzed 50 additional putative targets. Thirty of them were downregulated in infected or transfected cells expressing mivaRNAs. Some of these genes are important for cell growth, transcription, RNA metabolism and DNA repair. We believe that a mivaRNA-mediated fine tune of the expression of some of these genes could be important in adenovirus cell cycle

    Los Rajiformes (Chondrichthyes, Batomorphii) del Plioceno inferior de la Formación Arenas de Huelva, suroeste de España

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    EL Neógeno marino del suroeste de España ha sido objeto de numerosos estudios, su contenido fosilífero ha sido objeto de numerosos trabajos, abordando diferentes grupos como malacofauna (Andrés, 1982; González-Delgado, 1983), foraminíferos (Sierro, 1984; González-Regalado, 1986), nanoplancton calcáreo (Flores, 1985), ostrácodos (González-Regalado y Ruiz, 1990, 1991; Ruiz y González-Regalado, 1996), polen (Valle y Peñalba, 1987), así como aspectos generales de tafonomía y paleoecología (Mayoral, 1986) y vertebrados (Ruiz et al., 1997). Algunos de estos trabajos indicaban la presencia de restos ictiológicos, como dientes de seláceos y otolitos. En este trabajo se presentan los registros inéditos de los Rajiformes de Formación Arenas de Huelva, Provincia de Huelva, España (Fig. 1) de la tesis doctoral de García (2008)

    Longitudinal analysis on parasite diversity in honeybee colonies: new taxa, high frequency of mixed infections and seasonal patterns of variation

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    To evaluate the influence that parasites have on the losses of Apis mellifera it is essential to monitor their presence in the colonies over time. Here we analysed the occurrence of nosematids, trypanosomatids and neogregarines in five homogeneous colonies for up to 21 months until they collapsed. The study, which combined the use of several molecular markers with the application of a massive parallel sequencing technology, provided valuable insights into the epidemiology of these parasites: (I) it enabled the detection of parasite species rarely reported in honeybees (Nosema thomsoni, Crithidia bombi, Crithidia acanthocephali) and the identification of two novel taxa; (II) it revealed the existence of a high rate of co-infections (80% of the samples harboured more than one parasite species); (III) it uncovered an identical pattern of seasonal variation for nosematids and trypanosomatids, that was different from that of neogregarines; (IV) it showed that there were no significant differences in the fraction of positive samples, nor in the levels of species diversity, between interior and exterior bees; and (V) it unveiled that the variation in the number of parasite species was not directly linked with the failure of the colonies

    Algebraic Bethe Ansatz for Integrable Extended Hubbard Models Arising from Supersymmetric Group Solutions

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    Integrable extended Hubbard models arising from symmetric group solutions are examined in the framework of the graded Quantum Inverse Scattering Method. The Bethe ansatz equations for all these models are derived by using the algebraic Bethe ansatz method.Comment: 15 pages, RevTex, No figures, to be published in J. Phys.

    Pathobiology and transmission of highly and low pathogenic avian influenza viruses in European quail (Coturnix c. coturnix)

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    European quail (Coturnix c. coturnix) may share with Japanese quail (Coturnix c. japonica) its potential as an intermediate host and reservoir of avian influenza viruses (AIV). To elucidate this question, European quail were experimentally challenged with two highly pathogenic AIV (HPAIV) (H7N1/HP and H5N1/HP) and one low pathogenic AIV (LPAIV) (H7N2/LP). Contact animals were also used to assess the viral transmission among birds. Severe neurological signs and mortality rates of 67% (H7N1/HP) and 92% (H5N1/HP) were observed. Although histopathological findings were present in both HPAIV-infected groups, H5N1/HP-quail displayed a broader viral antigen distribution and extent of microscopic lesions. Neither clinical nor pathological involvement was observed in LPAIV-infected quail. Consistent long-term viral shedding and effective transmission to naive quail was demonstrated for the three studied AIV. Drinking water arose as a possible transmission route and feathers as a potential origin of HPAIV dissemination. The present study demonstrates that European quail may play a major role in AI epidemiology, highlighting the need to further understand its putative role as an intermediate host for avian/mammalian reassortant viruses
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